Download Environmental Investigation of Legionella in Health Care

Ministry of Health and Long-Term Care
Environmental
Investigation of
Legionella in Health
Care Institutional
Settings
Public Health Policy and Programs Branch
Population and Public Health Division
Ministry of Health and Long-Term Care
June, 2016
2
Table of Contents
Preamble ............................................................................................................................. 5
Purpose ............................................................................................................................... 5
Legionella Environmental Investigation ........................................................................... 6
Health and Safety of Public Health Inspectors ................................................................ 6
Environmental Assessment Survey ................................................................................. 7
Environmental Sampling ............................................................................................... 13
Types of Samples ....................................................................................................... 14
Temperature and Disinfectant Testing ........................................................................ 14
Temperature ............................................................................................................... 15
Disinfectant ................................................................................................................. 16
Logistics ...................................................................................................................... 17
Interpretation of Results .................................................................................................. 18
Considerations When Interpreting Samples: ................................................................. 18
Remediation and Emergency Control Measures ............................................................ 19
Disinfection.................................................................................................................... 19
Thermal Disinfection ................................................................................................... 19
Chemical Disinfection ................................................................................................. 20
Point-of-use Filters ........................................................................................................ 21
Post-Remediation Sampling .......................................................................................... 21
Legionella Management ................................................................................................... 21
Developing an Institutional Water Safety Plan .............................................................. 23
Glossary ............................................................................................................................ 24
List of Acronyms .............................................................................................................. 27
References ........................................................................................................................ 28
Appendix A: Background Information on Legionella .................................................... 33
Introduction ................................................................................................................... 33
Legionella in the natural environment............................................................................ 33
Factors favouring the growth and survival of Legionella................................................ 34
Temperature ............................................................................................................... 34
Biofilm ......................................................................................................................... 34
Other factors ............................................................................................................... 35
Health effects ................................................................................................................ 36
3
Mode of transmission .................................................................................................... 36
Risk factors or preconditions for developing Legionnaires’ disease .............................. 37
Persons at risk .............................................................................................................. 37
Legionella in institutional settings .................................................................................. 38
Sources of Legionella outbreaks in institutions ............................................................. 39
Diagnostic Tests ............................................................................................................ 40
Appendix B: Search Methodology................................................................................... 41
Scientific literature ......................................................................................................... 41
Database .................................................................................................................... 41
Limits .......................................................................................................................... 41
Search strategy ........................................................................................................... 41
Grey literature ............................................................................................................... 43
Database .................................................................................................................... 43
Search strategy ........................................................................................................... 43
Appendix C: Methods Environmental Investigation Process ........................................ 44
Appendix D: Example Environmental Assessment Form.............................................. 45
Appendix E: Collection Form ........................................................................................... 55
Appendix F: Water Safety Plan ........................................................................................ 56
Appendix G: Control Measures Implemented During Outbreaks.................................. 58
Appendix H: Stakeholders ............................................................................................... 72
4
Preamble
This guidance document supports implementation of the Risk Assessment and
Inspection of Facilities Protocol, 2008 (or as current) of the Health Hazard Prevention
and Management Program, under the Ontario Public Health Standards. Under the
Health Hazard Prevention and Management Program, Boards of Health (BOH) are
required to conduct surveillance of health care institutions and assess associated risk
factors and emerging trends related to illnesses and injuries in order to reduce the risk
of illness or injury to the public. BOH are also required to respond to complaints and
reports of adverse events related to Legionella in health care institutional settings, as
stated in the Institutional/Facility Outbreak Prevention and Control Protocol, 2015 (or as
current). This response is required within 24 hours of notification and includes
determining the level of potential impact and the appropriate corrective response.
Purpose
The purpose of this guidance document is to support BOH in meeting the minimum
expectations of the Risk Assessment and Inspection of Facilities Protocol, 2008 (or as
current), to reduce adverse health outcomes arising from reported Legionella events
through surveillance, assessment, inspection and management in health care
institutions.
Specifically, this guidance document is to be reviewed in conjunction with the
Background Information on Legionella (Appendix A and B), published by Public Health
Ontario (PHO) and will assist BOH to:






Collect and assess information about environmental conditions that may
pose a potential health hazard;
Conduct environmental investigations to assist in source identification;
Identify and assess the risk of exposure to Legionella within the
health care institution;
Apply appropriate methods for collecting environmental samples
reflective of the conditions at the time of sampling;
Effectively respond to outbreaks and complaints at health care institutional
settings; and
Develop and implement strategies to reduce the risk of exposure to Legionella.
5
Legionella Environmental
Investigation
Legionella species are bacteria that live as parasites in aquatic environments.1 They are
found within the natural water environment (rivers, lakes, ponds and reservoirs) and in
most soils and mud.2 The main method of contracting a Legionella infection
(legionellosis) is by inhalation. Individuals whose immune systems are suppressed and
unable to fight off infection are at an increased risk for acquiring legionellosis and are at
an increased risk of Legionnaires’ disease-related mortality. An environmental
investigation should be conducted when there is a suspected or confirmed case or
outbreak of health care-associated legionellosis. The purpose of the Legionella
environmental investigation is to identify the source(s) potentially associated with the
outbreak so that timely and appropriate remedial efforts can be made to prevent further
cases.3,4 The investigation process is summarized in Appendix C.
Determining which sources to select for environmental sampling should be based on the
public health inspector’s (PHI) environmental assessment of the health care institutional
setting, and may take into account epidemiological data suggesting an association
between cases and exposure to possible Legionella sources.5 The source of Legionella
may be confirmed through laboratory analysis, if the PHI’s environmental samples are
genetically matched to the clinical strain of Legionella.
Health and Safety of Public Health
Inspectors
Employers and PHIs are required to comply with all applicable Occupational Health and
Safety Act (OHSA) requirements. Employers have a general duty to protect the health
and safety of their employees.6 This involves:

Providing the necessary training and supply of safety equipment to ensure PHIs
can perform their duties safely; and

Taking any other reasonable precaution to protect PHIs.
The employer may require the use of suitable personal protective equipment (PPE) to
minimize the PHI’s exposure to Legionella bacteria during sample collection. Examples
of PPE in a Legionella investigation can include: respiratory protection, safety glasses,
hard hat and safety shoes, impermeable gloves, disposable overalls and high visibility
vests. The employer must provide instruction and training to ensure PHIs using PPE are
aware of its limitations and the requirements necessary for the proper care and use of
the equipment.7 Where possible, PHIs should consult with or be accompanied by a
6
health and safety committee member from the facility who is familiar with specific
requirements at the health care institution.
If the suspected or confirmed case is an employee in the health care institutional setting
or if employees may be at risk, the Ministry of Labour should be informed, and may
conduct a joint or separate investigation.
Note: For general information on how to reduce the risk of transmission of
microorganisms in health care settings please refer to the document Routine Practices
and Additional Precautions in All Health Care Settings.8
Environmental Assessment Survey
In the early stages of a Legionella investigation, the PHI should perform an
environmental assessment (see Appendix D for an example of an Environmental
Assessment Form) in order to identify and assess the risk of Legionella bacteria
exposure from any component of the facility’s water system.9 The completion of the
assessment form and epidemiological data will help determine sampling points.
Sampling points should be prioritized based on the most likely locations where the
source of Legionella bacteria may be found. For example, aerosol sources that the
case(s) may have been exposed to should be sampled first, followed by other high-risk
sources (i.e., sites that potentially contain the highest numbers of Legionella
bacteria).10,11,12 Sampling points should be continually reassessed as the investigation
progresses and as more results and information become available to locate the source
of the Legionella.12
Table 1 summarizes common sampling points for Legionella in health care institutional
settings.5 Additionally, the Public Health Inspector’s Guide to the Principles and
Practices of Environmental Microbiology provides a list of potential sampling sites
recommended by the Centers for Disease Control and Prevention (CDC). 11
7
Table 1: Possible sampling sites for Legionella in health care institutional settings i
Site samples
Potable water Incoming service
system
connection main
Type of
samples
Comments
Bulk water
•
Where the temperature of the
source water is greater than 20°C
or there is a high organic content,
or the heterotrophic bacteria count
is high, there is a potential for
Legionella to be present in the
water entering the system.
Water softener
Bulk water
•
Samples should be collected both
before and immediately
downstream of the softener to
determine whether the softener is
colonized.
Tanks and
cisterns
Bulk water
•
Dip samples can be taken where
the fresh incoming water enters
the tank/cistern.
Water heater
Bulk water and
biofilm swab if
drained
•
Bulk water sample can be taken
from the drain valve.
Taking biofilm swabs requires
complete draining of the tank.
Bulk water
•
Expansion vessel
(allows for
thermal
expansion of hot
water within a
water heater)
•
Should have a valve at the bottom
of the vessel to allow sampling.
i
Before samples are collected it is essential to involve PHOL at the onset, not only to make them aware
of the outbreak and to allow them to prepare, but also to obtain advice on the number and types of
samples required.
8
Site samples
Potable water
system
(Continued)
Shower and
faucets
Type of
samples
Bulk water and
biofilm swab of
shower head or
inside the
faucet. A biofilm
swab may be
taken from the
aerator.
Comments
•
•
•
•
•
Whirlpool spa
Water in the pool
Bulk water
•
•
Biofilm above the
water line
Biofilm swabs
•
Pre-flush samples (water collected
immediately after a faucet or
shower is opened) are typically
taken from hot and cold water
systems.
PHIs should remove the shower
head and faucet aerator prior to
sampling in order to minimize
aerosol production.
This will also help aid the
inspection and sampling of any
biofilm inside shower head or
faucet aerator.
The pre-flush sample is intended
to represent water held within the
tap or fitting and should be taken
when the tap has not been used
for several hours.
A small number of post-flush
samples may be taken to assess
the degree of contamination within
the pipework system as opposed
to within individual outlets.
Pool water may not yield large
numbers of Legionella; however,
solid material samples and biofilm
samples tend to have large
numbers of Legionella.
If the pool is drained, a water
sample can be collected from the
overflow tank.
Areas above the water line may
not be subject to disinfection.
9
Site samples
Whirlpool
spa
(Continued)
Comments
Water jets
Biofilm swabs
•
Several jets should be swabbed. If
possible the inner pipe should be
swabbed as well.
Filter
Solid material
(sand, diatom
powder, or
polyester filling
in cartridge
filters)
•
Even if the pool is drained, filter
material can still contain
Legionella.
Bulk water
•
Cooling towers can produce
aerosols that can travel over
considerable distances.1
If the health care institutional
setting where the outbreak has
occurred has air intakes that are
located near a cooling tower, then
several solid samples of the air
intake filters should be taken.
PHOL should be consulted to
determine the amount of filter
material that will be needed for
analysis.
It is advised that a maintenance
technician/engineer familiar with
cooling towers assist with access
to points from which samples are
to be taken.
Cooling tower Make up water
Decorative
fountain
Type of
samples
Collection basin
(area below the
tower for
collection of
cooled water)
Bulk water and
biofilm sample
at the water line
Sump (section of
the basin from
which water is
pumped back).
Silt and sludge
may also be
collected here
Bulk water and
biofilm swabs at
the water line
Return service to
the cooling tower
located near the
heat source
Bulk water
Fountain
reservoir
Bulk water
Fountain trough
Biofilm swabs
Material such as
foam in the
fountain
Solid material
•
•
•
•
In one outbreak, foam material
used to prevent splashing was
heavily contaminated with
Legionella.13
10
Site samples
Humidifiers
Water used for
humidification
Nebulizers
Water used for
cleaning the
device
Hand
powered
resuscitators
Type of
samples
Bulk water and
biofilm swab
Comments
•
•
Take at least one biofilm swab of
moist surface.
Take at least one biofilm swab of
moist surface.
Breathing
ventilators
Other
equipment
Please contact PHO for consultation on other equipment that may be used.
The environmental assessment survey should be based on various factors of the water
system including, but not limited to:1,10
•
A review of written protocols the health care institution may have for Legionella
risk reduction, such as a Water Safety Plan (WSP) or Legionella management
and control policy;
•
A review with the building services engineer or water treatment contractor, of an
up-to-date schematic diagram (if one exists) showing the layout of the potable
and non-potable water systems including:
o The incoming water supply, whether from a municipal water system or
from a private source;
o Whether water is recirculated or stored;
o Water softening filters, hot water storage tanks, expansion vessel, filters,
pumps and strainers;
o The type of fittings, including faucets, showers, toilet cisterns, aerators,
thermostatic mixing valves (TMV) and electronic faucets;
o Cooling towers or evaporative condensers;
o Other air conditioning systems or humidifiers within the building which may
produce aerosols;
o Equipment that contains water and might be a potential risk, such as
public spas, decorative fountains and ice machines;
11
o Water systems that are infrequently used (e.g., fire suppression systems,
emergency showers and eye wash stations); and
o Any points in the water system where there is a possibility of low flow or
no flow, such as blind ends, dead legs and parts of the system temporarily
out of use.

An interview with building services to obtain information regarding any recent
construction, renovation, maintenance workii and associated water outages;
cleaning, flushing and disinfection procedures; and site and date of any
emergency Legionella remediation measures;

A review of the physical and chemical water treatment methods and maintenance
regimes for little used water outlets (e.g., infrequently used sinks and showers).
When outlets are not in regular use, routine and frequent flushing for several
minutes can reduce the formation of biofilm and Legionella proliferation in the
system.

A review of any onsite monitoring results of the drinking water (e.g., disinfectant
levels, turbidity and temperature);

A review of any past laboratory microbiological results, such as Legionella
microbiological results;

An assessment of the physical and chemical conditions within the water system
likely to support the growth of Legionella, such as:
o Deposits of sludge, scale, corrosion, organic matter and biofilm;
o Areas where the water may reach 20° - 50°C in normal or abnormal use,
such as during construction. It should be noted that normal daily water
temperature fluctuations can occur, depending on how often the water
system is used;
o Where levels of disinfectant are inadequate or absent;
o Where the materials (rubber hoses) and/or components (electronic
faucets, aerators, hydrostatic shock absorbers) support microbial growth;
o Where thermostatis mixing valves are used;
o Where uninsulated cold and hot water distribution pipes are present; and
o Whenever cold water pipes are in close proximity to heat sources, such as
in ice machines or hot water pipes.
ii
To minimize occupant risk during construction/renovation activities health care institutions should follow
the “CSA Z317.13 Infection Control During Construction, Renovation and Maintenance of Healthcare
Facilities” or Health Canada’s Guideline “Construction-related Nosocomial Infections for Hospitalized
Patients: Decreasing the Risk of Aspergillus, Legionella and Other Infections
12

An assessment to determine possible sources of aerosolized water (e.g.,
aerosols generated by cooling towers, showers and faucets, humidifiers,
decorative fountains or spa pools);

The design and location of building structures, e.g., the position of air intakes
(including open windows) for the facility in relation to the location of cooling tower
exhausts;

Medical devices such as respiratory therapy equipment (e.g. bronchoscopes and
endoscopes), humidifiers and nebulizers; and

The population’s susceptibility to Legionnaires’ disease (LD).
Environmental Sampling
Environmental sampling for Legionella should only be performed for the investigation of
a confirmed or suspected clinical case or suspected outbreak. The PHI should contact
the Public Health Ontario Lab (PHOL) at the beginning of the Legionella investigation to:

Make them aware of the case/outbreak;

Allow them time to prepare testing materials (e.g., anticipated number of
samples); and

Obtain testing materials (e.g., environmental swabs, requisition forms).
PHO’s document, Public Health Inspector’s Guide to the Principles and Practices of
Environmental Microbiology outlines when testing should be performed and provides
basic guidance on the volume of water required, selection of sampling sites, type of
samples, sampling collection procedures and sample transportation instructions. 11 This
information should be provided to PHOL when environmental testing is requested, so
the PHOL can conduct culture-based analyses in an attempt to identify the source.
Ideally, sampling should occur prior to any disinfection of water systems. 1,5,10 PHIs
should enquire about any superchlorination or similar actions that may have been done
to the water system prior to sampling. However, disinfection does not have to be
delayed until sampling results are received (which may take up to 10 to 14 days). Once
PHIs have taken samples, the health care institution may immediately begin disinfection
and remediation procedures pending sampling results. This should be done immediately
to minimize any further exposure to Legionella. Temporarily discontinuing the use of
cooling towers, humidifiers, spas, showers, decorative fountains or other aerosolgenerating items may be considered as a precautionary action pending sampling
results. Caution should be exercised if discontinuing the use of items necessary for daily
hygienic activities, such as showers. In this situation, alternative water devices or
sources should be provided.
13
Types of Samples
The following types of samples can be collected when testing for Legionella:11



Water samples capture the free floating Legionella or any disturbed biofilm.
Instructions to determine the volume of water required for analysis may be
obtained from a PHOL. Generally for potable water, one litre should be
collected using five standard bacteriological water bottles per sampling site. For
non-potable water, 200 ml (one bottle) is generally required. During an outbreak
investigation, collecting water samples immediately after a fixture is opened
(pre-flush samples) is the preferred sample type as it poses the highest risk to
the user. To minimize aerosol production, allow the water to run slowly into the
sample bottles. The pre-flush sample is intended to represent water held within
the fixture itself and ideally, should be taken when the tap has not been used
for several hours.
Swab samples capture Legionella contained within a biofilm. Swab kits have a
relatively short expiry date and should be ordered directly from a PHOL
(Environmental Microbiology section) at the time of the investigation. Biofilm
shields Legionella and enhances its multiplication, so it is recommended that
swabs be taken in conjunction with water samples from sites where biofilms are
likely to form (e.g., cooling tower sumps, potable water faucets, hoses,
showerheads, and whirlpool spa filters).9,14
Solid material (bulk) samples capture Legionella found in materials such as
air or water filters that cannot be swabbed. The sterile plastic bags with round
wire closure used for collection of food samples can be used.11 The
Environmental Microbiology section of PHOL should be contacted for details on
the methodology for the collection and transportation of solid samples.
Temperature and Disinfectant Testing
Temperature and disinfectant residual testing of both hot and cold water systems should
be conducted while sampling for Legionella bacteria.3 A preprinted sample collection
form (see Appendix E) will save time during sample collection.5 See Table 2 for an
example of a completed sample collection form.
14
Table 2: Example of a Sample Collection Form
Sample
Date
Specimen
Sample
Temperature Chlorine
*
ID
collected
type
description
(°C)
level
(water/
(ppm)
swab/
filter)
Comments
123456
April 8,
2014
Water
Faucet in
50
room 2014
0.5
Patient with
confirmed
case of LD
stayed in this
room
234567
April 8,
2014
Swab
Shower
NA**
head in
room 2014
NA
Patient with
confirmed
case of LD
stayed in this
room; aerating
shower head
contained
biofilm
345678
April 8,
2014
Water
Shower in 51
room 2014
0 ppm
Patient with
confirmed
case of LD
stayed in this
room
*Each
sample must be labeled with the unique identifier that must also be affixed to the
requisition. PHOL water bottles have barcodes attached that can be used for this purpose.
**
Not applicable
Temperature
Recording the water temperature is extremely useful when sampling. The temperature
will give an indication of the parts of the system that would support the optimum growth
and survival of Legionella. The recommended water temperatures for Legionella control
are:

Hot water tank outlet temperature at or above 60°C;15

Hot water temperature in any part of the system at or above 55°C;16,17 and

Cold water temperature in any part of the system at or below 20°C.15
15
It is important to note that in health care institutions, the hot water temperature is often
reduced to prevent scalding of residents (between 40° and 49°C), making it ideal for the
multiplication of Legionella.9,29 In addition, the warmest point in a cold water system, or
the coolest part of a hot water system, are likely to support the survival and growth of
Legionella. For example, there may be areas of a hot water system which are cooler
due to poor insulation, or in contrast, systems intended to run cold water, such as ice
machines, may have areas at higher temperatures due to proximity to a compressor
emitting heat.19,20
Temperature measurements should be taken under normal operating conditions, using
a calibrated thermometer placed directly in the water flow.3 Temperatures at the point of
use may be reduced by blending hot and cold water (using TMVs) to prevent scalding,
while maintaining the hot water at the recommended temperature. Careful consideration
is needed when sampling hot and cold water systems with TMVs. If possible, samples
should be taken from separate hot and cold water outlets upstream of the TMV, in order
to be representative of the water flowing around the system and not only in the area
downstream of the TMV. In contrast, pre-flush samples of taps and showers
downstream of TMVs will detect colonization of the TMV, faucet or showerhead, and if
present, flexible hoses.10
Disinfectant
Disinfectants levels (i.e. residual chlorine) in the water system should also be tested.
Though municipal water systems must ensure drinking water has a chlorine residual of
at least 0.05mg/L, most water supplies will contain a chlorine residual in the range of 0.1
- 0.5 mg/L at the point where water enters the health care institution.16 This level of
chlorine may not be sufficient to inhibit the growth of Legionella within the water
system.20 Biofilm and organic matter within the pipework can rapidly decrease residual
chlorine levels, and aid in the growth of Legionella. 20 Where necessary, a health care
institution may apply secondary disinfectant to aid in the control of Legionella and
biofilm. 16
Where a water system is relatively free from established biofilm, maintaining a free
chlorine residual of 0.5 - 1.0 mg/L will help reduce the development of biofilm in the
pipework and control the growth of Legionella.16
Temperature and residual chlorine level samples should be taken from every outlet in
rooms linked with a patient who may be associated with a Legionella infection.3
However for control measures, approximately 10% of all temperature and residual
chlorine level samples collected should represent water outlets of rooms not directly
associated with a potential Legionella case.
Note on Monochloramine: In Ontario, some municipalities use monochloramine to
disinfect the water distribution system. Field studies have shown monochloramine to be
effective against Legionella in plumbing systems because of its stable residual and its
ability to penetrate biofilms.18,22
Conversion by municipalities in the United States to monochloramine as the disinfection
method has been shown to lower the prevalence of Legionella colonizing the potable
water system in buildings such as hospitals.22
16
Monochloramine appears to be a promising approach to decreasing Legionella
colonization; however, the efficacy of monochloramine treatment in individual health
care institutions has not been fully established.13 The United States Department of
Veterans Affairs suggest a minimum of 0.5 ppm monochloramine residual be detected
at water outlets.23
Logistics

It is recommended that the health care institution use a hired contractor, a health
and safety committee member or other facility employee who is familiar with the
water system and is responsible for its maintenance. The contractor or employee
should be able to remove showerheads and faucet aerators to assist PHIs with
sample collection.

Care and diligence in collecting evidence in the form of records, samples, and
photographs and chain of custody requirements should be adhered to. For
further information on collection instructions for legal samples please refer to the
PHO Public Health Inspector’s Guide to the Principles and Practices of
Environmental Microbiology.

Equipment and materials that should be used when conducting sampling
activities include:
o Personal Protective Equipment
o PHOL water collection bottles
o Bacteriological Analysis of Water Requisition Form
o Environmental swabs to collect biofilm samples
o Environmental Bacteriological Swab Test requisitions
o Chlorine test kit
o Calibrated thermometer
o Camera
o Sterile plastic bags (used for collecting solid material)
o A cooler supplied with ice or frozen refrigerator packs, for storage and
transportation.

PHOL requires that samples be stored at refrigeration temperature (2° to 6°C)
and transported to the laboratory as soon as possible. This may involve
contracting a courier company or making other arrangements to transport the
samples to the laboratory. For additional information on transporting Legionella
samples, contact PHOL.
17
Interpretation of Results
It is recommended to consult with a microbiologist for the interpretation of results.11
This individual should be aware of the following:

The type of water system sampled (potable water, public spa, cooling tower,
decorative fountain, etc.);

The sample point in relation to any water system risk factors such as stagnation,
maintenance/construction activities, low biocide levels, high cold water
temperatures and low hot water temperatures;

The patient’s vulnerability and whether the outlets sampled had been used by, or
were in the vicinity of the patient;3

The timing of the sample in relation to biocide dosing or thermal shock, as results
may not reflect the conditions at the sample point when the cases were infected;

The presence of an effective neutralizer in the sample bottles:
o Water sample bottles supplied by PHOL contain sodium thiosulphate to
neutralize any disinfectants which may be in the water; and
o Where non-oxidizing copper-silver ions are used as a biocide, a
neutralizeriii is required to prevent further disinfection of the sample by
copper;10 and
o Any delay between sampling and culturing during sample transport, such
as temperature changes, may affect the ability of the laboratory to recover
viable Legionella.
Considerations When Interpreting
Samples:

An increase in the counts of background flora may inhibit or overgrow any
Legionella present making it difficult to detect; and

The level of Legionella found at the time of sampling may not be reflective of the
time when the cases were initially infected because Legionella in the water and
biofilm is in a constant state of flux.
iii
For biocides containing silver and copper, the chelating agent ethylenediaminetetraacetic acid (EDTA)
can be used at concentrations of 10 mg/L.
18
Remediation and Emergency Control
Measures
Once the environmental source of Legionella has been identified the health care
institution should develop and implement a remediation action plan (see Appendix G for
recommended control measures during confirmed outbreaks). A team with expertise in
Legionella, including engineers and water treatment experts should be used to design
and implement the remediation plan that includes post remediation verification
sampling. BOH should review and provide feedback to the proposed remediation action
plan and provide advice and support as required.
Health care institutions not well versed in Legionella remediation and control may wish
to hire an environmental consultant. The consultant should have expertise and
experience related to the remediation and control of Legionella in health care
institutional settings.
Disinfection
The remediation plan should include disinfection procedures that are effective against
Legionella, and minimize the adverse impact on equipment, components and exposed
persons. Many disinfectants used to control Legionella and biofilm can be corrosive and
result in water leaks or leaching of metals into the potable water system.
The most common methods of remediating contaminated water systems is by thermal
disinfection, chemical disinfection, or both.21 Combining thermal and chemical
disinfection is more effective than either alone.23, 24
Thermal Disinfection
During thermal disinfection the water temperature should be increased and maintained
at 71° – 77°C, for at least 30 minutes while progressively flushing each outlet. Due to
the use of hot water, care should be taken to minimize aerosolization of water and
prevent injuries due to scalding. The following points should be noted about thermal
disinfection:

The optimal flush time will vary depending on the individual water system,
however up to 30 minutes is recommended.23

Dead legs or blind ends cannot be effectively flushed and will cause
recontamination of the water system;18

Thermal disinfection may not be an appropriate disinfection method for health
care institutions that use semi-instantaneous water heaters. These heaters may
not be able to produce enough hot water to keep up with the demand for the
19
required 30 minutes.25 To be effective, the entire system must reach the water
time/temperature requirements;1

Thermal disinfection will not disinfect downstream of TMVs. The TMVs will blend
cold water with the hot water, thereby lowering the temperature of the water
reaching the outlet. TMVs should be maintained, cleaned and disinfected in
accordance with the manufacturer’s instructions;

The water system should be assessed to ensure it can withstand the thermal
disinfection temperature/time requirement. If not, an alternative disinfection
method should be used;

After thermal disinfection treatment, tanks and hot water tanks should be drained
and cleaned (including descaled if necessary); and

Once Legionella within biofilm is established in a water system, raising the
temperature of the system may not eradicate them.

It is recommended that thermal disinfection be followed with chemical disinfection
of the water system.1
Chemical Disinfection
When implementing remediation measures, it is important to consider that chemical
disinfection may lead to the introduction of chemicals or the formation of disinfection byproducts into the health care institution’s water supply at potentially toxic
concentrations.
For disinfection chemicals to be effective, the physical cleaning of sediment, sludge,
scale and biofilm must be performed first before the application of the disinfectant.
The following chemicals are effective against Legionella due to their residual effects.22,16

Chlorine dioxide

Monochloramine

Silver stabilized hydrogen peroxide; and

Copper-silver ionization
The most common of these chemicals used for chemical disinfection is chlorine.20
When chlorine is used for disinfection:

The water system and equipment should be assessed to ensure it can withstand
the level of chemical disinfectant required (concentration and time);

The level of chlorine should be dosed at 50 mg/L for a minimum contact time of
one hour, at the end of which the free residual chlorine should be 30 mg/L 16;
20

All outlets should be flushed until the free chlorine residual is reached at all
faucets; and

After disinfection is complete, the outlet should be flushed, reaching the ideal
concentration of 0.5-1.0mg/L.
Point-of-use Filters
Commercially available micropore membrane filters fitted to water outlets are also
effective in preventing Legionella from being released at the point-of-use.21 Typically,
these filters are fitted to water outlets or installed in water supply lines of equipment
(e.g., ice machines and drinking fountains). Point-of-use filtration is not a disinfection
method and does not eliminate Legionella from the potable water system, but controls
Legionella at the point of use. Fouling of the filter will reduce flow and should be
replaced as recommended by the manufacturer.
Post-Remediation Sampling
After remediation, all previously contaminated sources should be resampled, to ensure
that the recolonization of Legionella has not occurred.26 It is recommended that testing
for Legionella be conducted every two weeks for three months, followed by testing
every three months, to ensure that the remediation is effective. 21 It is also
recommended that any detections of Legionella during this time frame be addressed
using the remediation action plan, and the test cycle restarted. 21
Legionella Management
Given the greater susceptibility of residents in health care institutions to Legionella,
ongoing management and maintenance of the water system is recommended to:

Control Legionella growth;

Monitor those aspects of the water system that are likely to contribute to
Legionella growth;

Evaluate the effectiveness of control measures through routine periodic testingiv
for Legionnella; and

Take corrective action if necessary.4
The evaluation of the effectiveness of preventative measures requires the consistent
use of action levels at different Legionella concentrations.12 The technical document,
ivPHOL does not provide testing of samples collected for routine environmental monitoring for Legionella, nor do
they perform enumeration of colony forming units (CFU) when culturing for Legionella. If required, another
laboratory should be used for these services. The private laboratory selected for processing of environmental
samples should be certified for proficiency in the CDC Environmental Legionella Isolation Techniques Evaluation
(ELITE) program (or an equivalent scheme accredited to ISO 17043:2010).
21
The control of Legionella bacteria in hot and cold water systems and detection in
healthcare premises, gives guidance on action levels, and action to be taken if
Legionella is found in health care institutional settings, and is shown in Table 3.16
Table 3: Actions to be taken following Legionella sampling in hot and cold water systems in health
care institutions with susceptible individuals
Legionella Count
(cfu/L)
Recommended actions for health care institutions

In a healthcare institution, the primary concern is
protecting susceptible individuals, so any detection of
Legionella should be investigated and, if necessary, the
water system should be re-sampled to aid interpretation of
the results, and ensure it is in line with the monitoring
strategy and risk assessment.

If the minority of samples are positive, the water system
should be re-sampled. If a similar count is found again, a
review of the control measures and risk assessment
should be carried out to identify any remedial actions to be
taken.

If the majority of samples are positive, the water system
may be colonized with a low level of Legionella. An
immediate review of control measures and risk
assessment should be carried out to identify any other
remedial action required, which may include disinfection of
the water system.

An immediate review of the control measures and risk
assessment should be carried out to identify any remedial
actions, including possible disinfection of the water
system.

The water system should be re-sampled, and retesting
should take place a few days after disinfection and at
frequent intervals thereafter, until a satisfactory level of
control is achieved.
Not detected or
<100 cfu/L
>100 cfu/L and
up to 1000 cfu/L
>1000 cfu/L
22
Developing an Institutional Water Safety
Plan
For health care institutional settings, it is advised that a water safety team (WST) be
established to develop a Water Safety Plan (WSP), the aim of which is to prevent the
growth of Legionella by implementing best practices for preventative maintenance along
with effective hazard control measures.16
The WST should consist of a multidisciplinary group, similar to infectious control
committees within the health care institution. The group should be familiar with water
systems and associated equipment in the health care institute and be knowledgeable of
Legionella bacteria.
The WSP is a risk management approach to the microbiological safety of water that
includes the need to:
 Assess the potential risk to patients, workers and visitors;
 Put into place appropriate management systems to ensure the potential risks are
controlled;
 Establish procedures for monitoring whether control measures taken are effective
and it not take corrective action and
 Ensure there are supporting programs, including documentation, communication
and training.16
The key components of a WSP are provided in WHO’s guidance document, Legionella
and the prevention of legionellosis (see Appendix F).9
Validation provides evidence that the WSP is effective and control measures are
operating properly.9 It involves providing data that show the overall effectiveness of the
plan in controlling Legionella. Routine testingv of the building’s water system for
Legionella is an example of a validation method.
If the WST chooses to validate the WSP by testing the building’s water system for
Legionella on a routine basis, a sampling protocol reflecting the topics covered in this
guidance document is recommended.
v
PHOL do not provide testing of samples collected for routine environmental monitoring for Legionella, nor do
they perform enumeration of colony forming units (CFU) when culturing for Legionella. If required, another
laboratory should be used for these services. The private laboratory selected for processing of environmental
samples should be certified for proficiency in the CDC Environmental Legionella Isolation Techniques Evaluation
(ELITE) program (or an equivalent scheme accredited to ISO 17043:2010).
23
Glossary
Aerators: Faucet aerators are used in health care institutional settings to conserve water.
They decrease water flow by forcing air through the water faucets.
Aerosol: A suspension of tiny free floating particles in the air that can carry Legionella
and be inhaled deep into the lungs. Water aerosols can be produced by showers and
taps, decorative fountains, whirlpool spas, cooling towers and humidifiers.
Biocide: A chemical agent which can control, inactivate, or kill microorganisms.
Biofilm: A slimly coating produced and inhabited by microorganisms, which enables cells
to stick to each other and adhere to a surface such as inside of a pipe or fitting.
Culture: The multiplication of living Legionella in growth media.
Colony forming units (CFU): A unit of measurement used to indicate the number of
viable microorganisms identified in a specific quantity of water.
Cooling tower: A device through which warm water is transferred to an air stream. This
results in evaporation, which cools the water.
Commissioning: Commissioning of a building’s water system (including all component
parts and attached equipment) means bringing the system into operation so that it is safe
for occupancy. From a Legionella perspective, the time period between filling the system
and occupancy is potentially the most hazardous. Any new water system requires, as a
minimum, flushing and disinfection before being brought into use. This should be done as
close to occupation as possible to minimize the possibility of Legionella growth.
Control measure: Any procedure used to prevent or eliminate a hazard or reduce the
hazard to an acceptable level.
Deadleg: A length of pipe in a water distribution system that has been capped or left in
place, through which water no longer flows. This results in water stagnation and
subsequent bacterial growth or proliferation.
Drift eliminator: Drift eliminators are usually installed to remove water droplets from the
air stream before they are emitted from the cooling tower. Droplet removal relies on
direction changes while passing through the eliminators. Drift eliminate comes in many
types of configurations include herringbone (blade-type), wave form, and cellular (or
honeycomb) designs. The cellular design is generally the most efficient because it
provides the greatest surface area for droplet removal. There must be no bypass of air
around the drift eliminators. The drift eliminators must be easily removable for cleaning,
inspection, and/or replacement.
Expansion Vessel: Within a pressurized water system, an internal bladder device is
often used as a means of accommodating water expansion (which is caused by the water
24
heating). These bladders are often made of synthetic rubber and, given suitable
conditions may support the growth of Legionella.
Flushing: The process of opening an outlet so that water flows out for a specified period
of time. The purpose of flushing is to prevent stagnating conditions in pipes, or to
dissipate a biocide after disinfection.
Hazard evaluation: A process to determine whether a health hazard exists when
workers may be exposed to hazardous materials.
Health care institutional setting: Any location where health care is provided, including
settings where emergency care is provided, such as hospitals and Long-Term Care
Homes.
Incubation period: The time interval between initial exposure and appearance of the first
symptom.
Legionella bacteria: The bacteria that can cause legionellosis in people. They are widely
distributed in natural water sources, soils and mud. There are many different species; the
most common in Ontario is L. pneumophila.
Legionellosis: The term used to describe any illness caused by exposure to Legionella
bacteria. The two most common types of legionellosis are Legionnaires’ disease and
Pontiac fever.
Legionnaires’ disease (LD): An acute lower respiratory tract infection accompanied by
pneumonia.
Outbreak: Two or more confirmed cases of legionellosis linked by common time and
place or to a common cause.
Personal protective equipment (PPE): Any clothing or equipment designed to protect
the user from injury or illness.
Point-of-use filter: A micropore filter specifically designed to preventing the passage of
Legionella bacteria, or other specific microorganisms and particle contaminants, which
may be present in water. Typically, these filters are fitted to water outlets or installed in
water supply lines proximal to equipment (e.g., ice machines, drinking fountains).
Pre-flush: Water collected immediately after the tap or fitting is opened. The tap or fitting
should not have previously been disinfected, or water run to waste. The pre-flush sample
represents water held within the tap or fitting, and ideally should be taken when the tap
has not been used for several hours.
Post-flush: Water collected after the tap has been running for a period of time (two
minutes or more. It may be reflective of the water quality circulating in the system.
25
Risk assessment: Identifying and assessing level of risk posed by a water system, work
procedure or process.
Risk management: Determining and implementing any necessary precautions to reduce
risk.
Serogroup: Subgroup of Legionella species distinguishable from other strains on the
basis of recognizable antigens on the surface of the microorganism.
Sporadic case: An isolated or individual case of disease with no links to other cases in
time or place, or to a common cause.
Susceptible individual: A person whose immune system is suppressed and may be
unable to fight off an infection caused by the inhalation of Legionella bacteria.
Thermostatic mixing valves (TMV): A valve that blends hot water with cold water to
prevent scalding.
Validation: Obtaining accurate and reliable confirmation that the WSP is effectively
controlling Legionella throughout the building’s water system.
Water systems: Refers to all water systems, potable and non-potable, within the building
and building site.
Water safety plan: The risk management approach for the prevention and control of
legionellosis associated with building water systems. It identifies and evaluates where
hazardous conditions may occur and details appropriate and practical control measures.
Whirlpool spa: Refers to spa pools, spa baths, whirlpools, hot tubs and hydrotherapy
pools.
26
List of Acronyms
Acronyms Full Term
BOH
Boards of Health
CDC
Centers for Disease Control Prevention
CFU
Colony Forming Units
LD
Legionnaires’ Disease
OHSA
Occupational Health and Safety Act
PHI
Public Health Inspectors
PHO
Public Health Ontario
PHOL
Public Health Ontario Laboratory
PPE
Personal Protective Equipment
TMV
Thermostatic Mixing Valves
WSP
Water Safety Plan
WST
Water Safety Team
27
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32
Appendix A: Background Information
on Legionella
Introduction
The World Health Organization (WHO) notes that although institutionally-acquired cases
of LD account for only a small proportion of all the reported cases, the fatality rate tends
to be much higher with institutionally-acquired LD than with community-acquired
infections.9 Because of this, if even one suspected LD case or outbreak occurs within a
health care institution, it is important that it be given a high priority and investigated
promptly. An outbreak investigation is a race against time, and the environmental
investigation, which is an integral part of the investigation, must gather as many facts as
quickly as possible in order to identify the source(s) of the outbreak.
Appendix A summarizes background information to support public health units (PHUs) in
conducting environmental health investigations related to Legionella in health care
institutional settings (broadly considered to include hospitals, long-term care facilities and
retirement homes).
Legionella in the natural environment
Legionella species are bacteria that can live as intracellular parasites in a variety of
species of protozoa in aquatic environments.5 They are found within the natural water
environment (rivers, lakes, ponds and reservoirs) and in most soils and mud. 2 In the
natural environment, although widespread, Legionella occurs in low numbers and the
conditions are rarely conducive to being a concern to human health. There are over 50
Legionella species and 70 distinct serogroups currently known. However, the majority of
Legionnaires’ disease (LD) is caused by Legionella (L) pneumophila, with serogroup1
being the predominant serogroup.
In Ontario during 2013, of the 8,530 samples submitted to PHOL from patients with
respiratory symptoms, 3.2% (269/8,530) were positive for Legionella species.
L. pneumophila was identified in 92% (247/269) of positive specimens with
L. pneumophila serogroup 1 representing 87% (233/269) of the positive specimens.
Only 8% (22/269) of positive specimens were L. non-pneumophila species.
However, these results should be interpreted with caution because at PHOL, the
predominant testing method for Legionella is urine testing, which can detect only
L. pneumophila serogroup 1. Therefore, other Legionella species and other
L. pneumophila serogroups may be underestimated as causes of LD.
33
Factors favouring the growth and survival
of Legionella
There are a number of factors that contribute to an environment that allows Legionella to
multiply.
Temperature
 Temperature appears to be one of the most important influences as to whether or
not the bacteria will grow. Legionella can survive and multiply between the
temperatures 20° – 50°C with an optimal temperature between 32° – 42°C.19
Legionella can withstand temperatures of up to 50°C for several hours, but are
destroyed within a few minutes at 60°C and killed almost instantly at 70°C.1,9 In
health care institutions, the hot water temperature is often reduced to prevent
scalding of residents, making it ideal for the multiplication of Legionella.9,18 For
example, Ontario Regulation 79/10 made under the Long-Term Care Act requires
the hot water temperature to be between 40° and 49°C.
 Although it is uncommon to find proliferation below 20°C, Legionella can remain
viable and dormant in cool water and, when not killed by adequate disinfection,
multiply when the temperature reaches a suitable level.2 Arvand et al., in a study of
cold water systems in health care institutions, found that 94 of 265 (35%) cold water
samples (<20°C) were contaminated with Legionella. 2 The authors concluded that
the cold water supplies of health care institutions may be heavily contaminated with
Legionella species. Indeed, although low temperatures inhibit Legionella growth, the
bacteria can survive in ice and, given the opportunity, cause LD. 27
Biofilm
 Another factor that is important for the survival and proliferation of Legionella is the
formation of biofilms. A biofilm is a slimy matrix produced and inhabited by bacteria,
which enables them to adhere to a surface.9, 28 In addition to providing nutrients, the
biofilm protects the Legionella bacteria from external stresses such as disinfectants,
increases in temperature, and attempts at physical removal. 9, 28 The presence of
scale and corrosion in a water system increases the available surface area and
encourages the formation of biofilms. 9 Environmental pressure changes that occur
when water systems are stopped and restarted (e.g., due to construction or
maintenance) can slough off or dislodge portions of biofilm and lead to large
numbers of Legionella bacteria entering the water system.29
34
 The growth and survival of Legionella is promoted by their ability to incorporate and
rapidly multiply within certain species of protozoa (intracellular growth) also found in
biofilm. Once these protozoa die, large numbers of Legionella bacteria can be
released into the water system.2, 9, 14
 Research has shown that the number of Legionella organisms from biofilm swabs is
greater than the number of Legionella organisms sampled from water.10 This can be
explained by the fact that the swab technique results in direct sampling of the
organisms present in the biofilm, which gives a greater yield than sampling of
water.30 It has been recommended that swab samples be collected as part of any
environmental Legionella sampling protocol. 14
The presence of biofilm and the bacteria’s ability to incorporate within protozoa
can permit Legionella to survive standard water disinfection procedures. Because
of this ability, Legionella can enter and colonize an institution’s potable water
distribution system and its components (e.g. showers, whirlpool spas and water
fountains).27, 28 Unless appropriate control measures are in place, the bacteria may
multiply, thereby increasing the risk of LD.
 Free chlorine residual levels in municipal water are generally enough to kill or inhibit
free-floating Legionella; however, free chlorine is rapidly dissipated by hot water and
consumed by biofilms, so by the time it reaches the distal end (far end of the water
distribution system) the concentration may be too low to inactivate the Legionella
bacteria.31
Other factors
 The materials used within a system may also be a factor favouring Legionella
growth. For example, natural organic compounds such as rubber gaskets and
rubber hoses provide a good nutritional source for bacteria and other
microorganisms to grow.9, 32
 The buildup of sediment can harbour Legionella bacteria and also provide a nutrient
source for them. 32
 Institutional facilities may be old and may have undergone extensive renovations
over time. As a result, they often contain redundant pipework/dead legs in which
water can stagnate (i.e., stand still for a period of time) which facilitates the growth
of Legionella. Also, the older pipe systems are more prone to the growth of
Legionella because of corrosion, scaling, biofilms and sediment.1
35
 In order to prevent scalding, TMVs are used to blend hot and cold water to provide
water at a predetermined temperature, typically between 38°C and 46°C. 1, 16 The
blended water downstream of TMVs may provide an environment in which
Legionella can multiply, thus increasing the risks of exposure.16 Where TMVs are
fitted, they should be as close to the point of use as possible to minimize the storage
of blended water. Ideally, TMVs should be incorporated directly in the tap fitting. 16
Health effects
Legionella bacteria can cause two distinct types of infection, collectively known as
legionellosis: Pontiac fever and LD.
 Pontiac fever is a milder self-limiting flu-like illness with an incubation period of five
hours to three days (most commonly 24 – 48 hours).9 There is no evidence of
pneumonia. Patients usually recover within 2-5 days without seeking medical help.
 Legionnaires’ disease is a severe and potentially fatal form of pneumonia with an
incubation period of 2 – 14 days22, 23 [most commonly 2 – 10 days34]. Symptoms
include a flu-like illness, followed by a dry cough and progression to pneumonia.
Diarrhea, vomiting and mental confusion are common.26
Mode of transmission
The mere presence of Legionella bacteria in building water is not sufficient to cause LD.
LD is principally acquired when a susceptible host inhales a sufficient dose of aerosolized
water droplets containing the bacteria. There is evidence that the most virulent strains of
Legionella are able to survive longer in aerosols than their less virulent counterparts. 18
Aspiration (inhalation of foreign matter into the lungs as opposed to swallowing) of water
contaminated with Legionella has also been described as a route of transmission. Some
researchers believe that in health care settings, aspiration is the major mode of
transmission.35 Aspiration has occurred in persons with swallowing disorders or in
conjunction with nasogastric feeding and endotracheal tubes.9 Legionnaires’ disease is
not transmitted from person to person or acquired through ingestion unless aspiration into
the lungs occurs.23 There is no established relationship between concentration of
Legionella in water and risk of becoming infected. Therefore, it is not possible to set riskbased concentration standards for Legionella in water.
Although Legionella may be found within large water droplets generated from a
source, the water component can evaporate producing very small particles (1 – 3
µm). These particles can remain suspended in air (an aerosol) for prolonged
periods of time depending on environmental factors such as humidity and air
movement and are small enough to penetrate, and be retained in, the deepest part
of the lungs (alveoli) where they can cause LD in a susceptible host.3
36
Risk factors or preconditions for
developing Legionnaires’ disease
Factors that increase the risk of someone acquiring LD include36:
 the presence and virulence of the strain of the Legionella species
 conditions suitable for growth of Legionella, e.g., inadequate concentration of
disinfectant, suitable water temperature (20° – 50°C) and deposits that are a source
of nutrients for the organism, such as sludge, scale, rust, algae, other organic matter
and biofilms
 a means of creating and spreading breathable droplets, e.g., the aerosol or mist
generated by cooling towers, air conditioners, humidifiers, showers, faucets or
whirlpool spas
 exposure of susceptible persons to water aerosols containing Legionella that is
inhaled or aspirated into the lungs. Transplant patients whose immune systems are
suppressed may become infected with a much smaller number of Legionella
organisms than patients who immune systems are not suppressed
Persons at risk
The very low attack rates associated with Legionella indicate that the general population
is quite resistant to this organism.31 This is because Legionella is an opportunistic
pathogen. A normal healthy person is able to fight off being infected, whereas a person
whose immune system is suppressed may be unable to fight the infection. 4 In an
institutional setting, some groups are clearly at increased risk of contracting LD. Those at
higher risk include:9
 immunosuppressed organ transplant recipients
 persons receiving immunosuppressive medication
 persons with an underlying condition such as lung and heart disease, diabetes or
kidney disease
 infants in neonatal intensive care units, because of their underdeveloped immune
systems, intensive ventilation procedures, and corticosteroid therapy
 smokers, those with excessive alcohol intake, and the elderly
Additional risk factors for health care-associated infections include patients who require
intubation (insertion of a tube down into the lungs to assist breathing), ventilation
assistance, respiratory therapy equipment, humidifiers or nebulizers (devices used to
deliver medication in the form of a mist inhaled into the lungs).
37
Legionella in institutional settings
People with recognized risk factors for LD are likely to be present in health care
institutions. These are settings in which there are activities and procedures capable of
generating aerosolized droplets that can be inhaled deep into the lungs; droplets that may
be contaminated with Legionella.17
Elderly people are at higher risk of developing LD than young and middle-aged
adults. Outbreaks of legionellosis have been reported among residents of
retirement homes.9 Additionally, swallowing difficulties, which are more
pronounced in the elderly, further exacerbate the risk of aspirating Legionella into
the lungs.37
Several factors make institutional water systems vulnerable to colonization by Legionella:
complexity and age of the water system; favourable water temperature for Legionella to
grow [25° – 42°C22]; deposits in the water system that are a source of nutrients for
Legionella, such as sludge, scale, rust and algae; and biofilm formation, which not only
protects the bacteria but allows it to proliferate.17 Although these conditions exist in other
buildings, the increased susceptibility of the institutional population puts them at a much
higher risk for infection from Legionella. 17
The greater the complexity of the water piping system, the greater the risk there
may be areas where Legionella colonization is present.38
Although attributable mortality for LD is only about 20% of all of reported cases, mortality
for health care-associated cases can be as high as 40%.22 The mortality rate for
institutionally-acquired LD is highly variable and reflects the different resident populations,
the virulence of the Legionella spp. and the promptness of specific therapy. Mortality
rates for hospital-acquired legionellosis are about three times higher than for communityacquired legionellosis. 22
In general, the incidence of LD may be underdiagnosed and under-reported for several
reasons:39
 When a patient is diagnosed with pneumonia, treatment is generally started
immediately. If the case is treated with antibiotics that are effective against
Legionella, the patient may recover without needing to establish if Legionella was
the cause of the pneumonia.
 Patients with LD may be missed because the diagnostic test used lacks sensitivity
and may have produced a false negative result.
38
 If immunosuppressed patients with a serious underlying disease (i.e., at particularly
high risk of acquiring LD) die, death may be attributed to their serious condition,
without diagnosing the Legionella infection.
 The severity of LD varies; therefore, many milder cases may not be suspected and
will go undiagnosed.
Sources of Legionella outbreaks in
institutions
Legionella species have been shown to colonize 12% - 85% of hospital water systems.40
Several environmental surveys, including one in Canada, have demonstrated the
presence of L.pneumophila in hospital water distribution systems. A hospital in Halifax,
Nova Scotia, over a four year period reported that of the 2,200 potable water samples
cultured from 20 sites, nearly 25% were positive for L. pneumophila serogroup 1.41 In a
United Kingdom study, 55% of water samples taken from 69 of 81 United Kingdom organ
transplant units tested positive for Legionella, and 45% tested positive for L.
pneumophila.42 In Queensland, Australia, following an outbreak at a hospital in 2013, the
Minister of Health directed that testing for Legionella be conducted at all hospitals. Of the
267 facilities that reported results, 106 (40%) facilities had positive results in one or more
samples for L. pneumophila, L. non-pneumophila or both.4
It must be kept in mind that the presence of Legionella colonization of the water system
may not be predictive of the occurrence of Legionella infection because Legionella may
be present in water without causing disease.5 However, potable hot water systems have
been the environmental source for the majority of reported institutional outbreaks. 18, 22
While cooling towers have been the most publicized source of LD outbreaks, only
in a few cases have institutional outbreaks actually been linked to a cooling
tower.19 One notable outbreak involving a cooling tower was the 2005 outbreak in
Toronto where there was a strong suggestion that the release of Legionella from a
nursing home’s cooling tower was the cause of the outbreak where twenty three
residents died.
In addition to water systems (namely showers and faucets),21, 25, 37, 43-47 other identified
institutional sources of LD reported in the literature include contaminated cooling towers
that were located near a hospital ventilation air intake,48, 49 respiratory therapy equipment
[bronchoscopes27 and endoscopes50 that were exposed to contaminated tap water, ice
machines,19, 20, 50 hydrostatic shock absorbers,51 aspiration of contaminated water
associated with nasogastric feeding,52 humidifiers,53, 54 nebulizers,55 decorative
fountains13 birthing pools,56 and physiotherapy pools.57 Appendix G summarizes the main
institutionally-associated outbreaks found in the literature.
39
Non-touch electronic faucets are becoming more common in many settings as a
way to improve hand hygiene and reduce water consumption. However, in a recent
study, Sydnor et al. found that non-touch electronic faucets were more likely to
become contaminated with L. pneumophila than manually operated faucets. The
authors also found higher rates of bacterial contamination of electronic faucets
after chlorine dioxide remediation, suggesting that electronic faucets may be more
difficult to disinfect. Their findings suggest that the combination of low water-flow
rates and internal components may provide surfaces for biofilm formation and
concentrated bacterial growth. They concluded that electronic faucets are more
likely than manual faucets to become contaminated, and serve as bacterial
reservoirs that may pose an increased risk to susceptible patients.57
In health care-associated LD, small outbreaks that occur over a period of time point to the
potable water system as the source of exposure. However, a sudden appearance of a
large numbers of LD over a short timeframe suggests a more widespread source of
aerosol; e.g., cooling towers.18
Diagnostic Tests
For information on the advantages and disadvantages of diagnostic tests produced
by the Centers for Disease Control and Prevention (CDC) please visit:
http://www.cdc.gov/legionella/diagnostic-testing.html
 The source of the Legionella is usually identified by a genetic match between the
environmental strain and the clinical strain. The Legionella urine antigen test is the
most common method for diagnosing Legionnaires’ disease; however, genetic
matching cannot be done using this test. Currently, genetic matching can only be
done using culture-based analysis. Culturing sputum for Legionella is not routinely
requested when the urine antigen test is performed. Consequently, when the urine
antigen test is positive, no sputum is generally available for Legionella culture.22
 The urinary antigen test used to identify LD detects only L. pneumophila serogroup
1 infections. Therefore, if the infecting strain is not serogroup 1 it may go
undetected.
40
Appendix B: Search Methodology
This technical document was prepared by searching scientific and grey literature on
Legionella as follows:
Scientific literature
Database
Databases searched were Ovid Medline, Embase, Environment Complete, Health
Business Elite, and Health Technology Assessments. Articles were limited to English
language and from 1995 to current.
Limits
For articles on Legionnaires’ disease:
 Date limited to 1995 to February 2014
 Language limited to English
 Limited to ‘humans’
 Limited to review articles only
For articles mentioning outbreaks of Legionnaires’ disease:
 Date limited to 1995 to February 2014
 Language limited to English
 Limited to ‘humans’
Search strategy
The search ran on February 10, 2014. Articles that detailed the molecular structure of
Legionella, the drug treatment of legionellosis, community-acquired legionellosis and
clinical articles were weeded out.
41
#
Searches
Results
1
Legionella pneumophila/
2521
2
Legionnaires' disease/
4048
3
1 or 2
5395
4
("Legionella pneumophila" or Legionnaires* or "pontiac fever" or (veteran*
adj1 disease)).mp.
7067
5
limit 4 to ("in data review" or in process or "pubmed not medline")
235
6
3 or 5
5630
7
limit 6 to (humans and yr="2008 -Current")
709
8
limit 3 to (English language and "review articles" and humans and yr="1995 Current")
189
9
from 8 keep 2, 5-6, 14, 18, 24-28, 32...
92
10
disease outbreaks/ or epidemics/
62438
11
(outbreak? or epidemic? or sporadic).ti. or (outbreak? or epidemic? or
sporadic).ab. /freq=2
77700
12
limit 11 to ("in data review" or in process or "pubmed not medline")
5196
13
10 or 12
67634
14
6 and 13
643
15
limit 14 to (English language and humans and yr="1995 -Current")
291
42
Grey literature
Database
Web based search
Search strategy
A web search was performed using Google to identify grey literature regarding best
practices in investigating Legionella. We used customized search engines to search the
websites of all Canadian provincial and territorial health ministries, all Ontario PHUs, and
the state governments of the United States. We also searched Google and limited results
to those of site:.gov.au and to site:.gov.uk.
Legionella test|testing|investigation|investigating|inspectors|investigators
standards|protocols|safety
Legionella "public health inspectors"|"local health officials" PPE|protection|"safety and
health"|"health and safety"
43
Appendix C: Methods Environmental
Investigation Process
Health unit is informed of a suspected Legionella case, or outbreak
A decision is made to conduct an environmental investigation. The Ministry of Labour
should be informed if workers are involved
Prior to Arrival
Ensure the following:

the system has not been remediated prior to environmental sampling

PHOL is informed of potential incoming samples

you have all necessary forms, bacteriological water sample bottles, swab
kits, camera, flashlight, thermometer, pH and chlorine residual test kit
On Site
Once on site, make contact with building or maintenance manager
 Review:
o
o

Identify:
o
o

water system schematics
water treatment reports
possible sites that have the potential to cause aersolization of water droplets
location of fresh air intakes relative to potential sources
Conduct a risk assessment and take environmental samples
o
o
focus on areas that are conducive to Legionella amplification and aerosolization
potential sources include cooling towers, warm water systems, humidifiers,
spas, decorative fountains, stagnant water in fire sprinkler systems
Post-visit Interpretation of Results
Submit environmental samples and associated forms to PHOL for analysis.
Following analysis, test results should be interpreted in conjunction with a
clinical/medical microbiologist.
 if a potential source is identified, appropriate remediation should commence
• re-sampling should be conducted to verify remediation measures were
effective
 a water safety plan should be implemented to prevent future outbreaks
44
Appendix D: Example Environmental
Assessment Form
This form can be completed by public health inspectors, in consultation with the
owner/representative of the health care facility. This template can be modified; additional
items may be added or removed to assist with the assessment.
Board of Health name and address:
______________________________________________________________________
Name and address of health care institution:
______________________________________________________________________
Public health inspector’s (PHI) name (s) and contact information:
______________________________________________________________________
Person interviewed:
______________________________________________________________________
Date of assessment: __________________ Time of assessment: _________________
A. Facility Characteristics:
1. Type of facility:
Hospital
Long-term care facility
Residential care home
Nursing home
Other: _______________________________________________
2. Does the facility house susceptible individuals (e.g., organ transplant recipients,
those on immunosuppressive medication, persons with underlying conditions such
as lung and heart disease, diabetes or kidney disease, infants in neonatal intensive
care units, smokers, those with excess alcohol intake and the elderly)?
Yes
No
45
3. Are health procedures performed that can increase the risk of legionellosis by
inhalation (use of ventilation humidifier) or aspiration (nasogastric feeding tube)?
(e.g., nebulizers, bronchoscopes and endoscopes, nasogastric feeding)
No
Yes
4. Can windows in any occupant rooms be opened? Yes
No
5. Are there decorative fountains, misters, humidifiers, water features, or any other
aerosol-generating devices anywhere on the facility premises? Yes
No
If yes, please describe and indicate their location and operation:
___________________________________________________________________
___________________________________________________________________
6. Has this facility been associated with a previous legionellosis cluster or outbreak?
Yes
No
If yes, please describe (e.g., location, source, number of cases, dates):
_____________________________________________________________________
___________________________________________________________________
7. Does the facility have a Legionella prevention or monitoring program (water safety
plan)?
Yes
No
If yes, pleased describe:
___________________________________________________________________
___________________________________________________________________
__________________________________________________________
8. Does the facility routinely monitor for Legionella? Yes
No
If yes, please note date and location where positive results have been reported:
_____________________________________________________________________
___________________________________________________________
B. Water Supply
1. What is the source of the water used by the facility?
Municipal
Water
Well
Other: ________________________________
2. How is municipal water disinfected?
Chlorine
Other:__________________
46
C. Design of the Existing Potable Water System(s) [Note: A schematic diagram on a
separate page and facility blueprints are useful for demonstrating the design]:
1. What type of heating system is used for the potable hot water system?
Instantaneous heaters without storage of hot water
Heaters with hot water storage tanks
Other: ________________________________________________________
Usual temperature setting ______°C
2. Is there a recirculation system (a system in which water flows continuously through
the piping to ensure constant hot water to all endpoints) for the hot water?
Yes
No
If yes, please describe (including delivery and return temperatures):
___________________________________________________________________
___________________________________________________________________
3. Is the maximum hot water temperature regulated to prevent scalding?
Yes
No
If yes, please record temperature: _______°C
4. Are hot and cold pipes and tanks insulated? Yes
No
5. What is the lowest documented hot water temperatures measured at any point
within the facility? ________ °C
When were the measurements made (Month/Date/Year)? _____/______/______
6. What is the highest documented cold water temperatures measured at any point
within the facility? ________ °C
When were the measurements made (Month/Date/Year)? _____/______/______
7. Are thermostatic mixing valves used anywhere in occupant areas?
Yes
No
If yes, please describe where? (Include routine maintenance):
___________________________________________________________________
___________________________________________________________________
47
8. Are rubber hoses used on showers or faucets? Yes
No
If yes, please describe (include routine maintenance):
___________________________________________________________________
___________________________________________________________________
9. Does the facility have a water softener or other water treatment devices on site?
Yes
No
If yes, please describe (including routine maintenance):
___________________________________________________________________
___________________________________________________________________
10.
Are electronic faucets or shock absorbers used? Yes
No
If yes, please describe (including routine maintenance):
___________________________________________________________________
___________________________________________________________________
11.
Is there a supplemental disinfection system used to disinfect the water?
Yes
No
If yes, please describe:
___________________________________________________________________
___________________________________________________________________
12.
Are the potable water chlorine residual levels measured? Yes
No
If yes, how often __________________________________________________
If yes, what is the range of residuals? _________________________________
13.
Please describe any regularly scheduled maintenance carried out on the hot
water system (e.g., thermal or chemical disinfection of little used outlets):
___________________________________________________________________
___________________________________________________________________
14.
Are there any water outlets or components that are infrequently used (e.g., fire
suppression systems) or are there any points in the water system where there is a
possibility of low or no flow, such as dead legs or parts of the system temporarily out
of use? Yes
No
If yes, please describe:
___________________________________________________________________
___________________________________________________________________
48
15.
Measured physical/chemical parameters:
Record the physical/chemical characteristics of the potable water system on the
following table. For each sampling point (e.g., faucet in an occupant room) turn on
the hot water tap. Collect the first 50mL from the tap. Measure the temperature, and
chlorine residual. Document the findings in the table on the following page.
Measured physical/chemical parameters
Location
16.
Date and
Time
Temperature
(oC)
Were samples taken?: Yes
Chlorine
residual
level (ppm)
Comments
No
If yes, please fill out the sample collection form (Appendix E).
49
D. Whirlpool spas, hot tubs & hydrotherapy pools
1. How many total whirlpool spas and/or hot tubs and/or hydrotherapy pools are
located on the premises? _______
2. Please record the spa features in the table below:
Spa number
1
2
3
4
Location
Max. bather load
Filter type
Age of filter
Filter maintenance
routine (e.g.,
backwashing
frequency)
Type of disinfectant
used (include
chemical name,
formulation, and
amount used)
Method used for
adding disinfectant
Date last drained
and scrubbed
3. Have any of the whirlpool spas been “shocked recently? Yes
No
If yes, please record when and why: _____________________________________
___________________________________________________________________
Were samples taken? Yes
No
If yes, please fill out sample collection form (Appendix E)
50
E. Cooling Tower and Evaporative Condensersvi
1. Name of device and location:
___________________________________________________________________
2. Contractor:
___________________________________________________________________
3. What is the source of water for the cooling towers and evaporative condensers?
___________________________________________________________________
4. Type of disinfectant used:
___________________________________________________________________
5. Frequency of disinfection:
___________________________________________________________________
6. Is a drift eliminator used?: Yes
No
Is it effective? _______________________________________________________
7. Distance to near air intake/open windows: _________________________________
8. Surfaces free from slime/scale/corrosion: Yes
No
If no, please describe the extent:
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
9. Is there a log book? Yes
If yes, is it up-to-date? Yes
10.
No
No
Date last sampled: (Month/Date/Year)? ______/______/______ Never _______
Results: ____________________________________________________________
vi
An example of a Cooling Tower Risk Management Plan can be found at: www.hamilton.ca/legionella
51
Please fill out the recent (last 6 months) special (non-routine) treatments, maintenance
or repairs to cooling devices:
Location
11.
Name of device
Action
taken
Were samples taken? Yes
Date
Name
Comments
No
If yes, please fill out sample collection form (Appendix E).
F. For recent (last 6 months) or ongoing construction, repairs or renovations
1. Was temporary water service provided to the new construction area? Yes
No
If yes, please describe: _______________________________________________
2. Has jack-hammering or pile-driving been used during the construction process at
this facility or nearby? Yes
No
If yes, please describe: _______________________________________________
3. If the new building construction includes an extension of the existing potable water
system, please report what part of the new building the existing potable water
system serves (consider dead legs resulting from construction)?
___________________________________________________________________
4. If the new building construction includes an extension of the existing potable water
system, have disruptions/changes to existing potable water system during the
construction been reported? Yes
No
If yes, please describe: _______________________________________________
52
5. Is there a standard operating procedure (SOP)vii for shutting down, isolating and
refilling/flushing for water service areas that have been subjected to repair and/or
construction interruptions? Yes
No
If yes, please describe the steps used in the SOP (attached a copy):
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
6. Has the potable water changed in terms of taste or colour during the construction
process?
Yes
No
If yes, please describe the changes including when the potable water change
started and ended:
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
7. Have there been any water main breaks, interruptions, or potable water
malfunctions in the past 6 months? Yes
No
If yes, please describe (e.g., which buildings were affected, beginning and end
dates):
___________________________________________________________________
___________________________________________________________________
If “Yes”, was any soil material introduced into the pipe(s) during these times?
Yes
No
If yes, please describe any steps taken to remediate the water:
___________________________________________________________________
vii AWWA
C651-14 Disinfecting Water Mains; ISBN: 9781625760463; Publisher: American Water Works
Association; 2014; AWWA catalog no: 43651-201
53
8. Before occupying the new building space, was a commissioning process
undertaken?
Yes
No
If yes, please describe (e.g., who performed the commissioning, when was it
completed):
___________________________________________________________________
___________________________________________________________________
If yes, is a commissioning report available for review? Yes
No
9. Additional comments:
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
___________________________________________________________________
54
Appendix E: Collection Form
Table 4: Sample collection form
Sample
ID*
Date
collected
Specimen type
(water/swab/filter)
Sample
description
Temperature
(°C)
Chlorine level
(ppm)
Comments
*
Each sample must be labeled with the unique identifier that must also be affixed to the requisition. PHOL water bottles
have barcodes attached that can be used for this purpose.
55
Appendix F: Water Safety Plan
Table 5: Water safety plan overview (adopted from WHO with minor modifications9)
Process step
Water source
Distribution
Respiratory apparatus
Assess hazards and
prioritize risks
(example)
High nutrients and
microbial load in
source water
Stagnant water in
deadlegs in the
pipework, resulting in
proliferation of
Legionella
Legionella entering respiratory
apparatus in tap water, being
inhaled by patient and leading to
potential Legionnaires’ disease
Identify control
measures (example)
Routine disinfection of
water at >0.5 mg/L
free residual chlorine
Routine cleaning
(flushing) procedures
for distribution system
and review of system
flow diagram to
identify areas of
concern or stagnation
Use of sterilized or point-of-use
filtered water to clean respiratory
equipment
Chlorine dioxide
Monitoring of water sterilization
devices
Monitor control
measures (example)
In line automated
chlorinator with
chlorine residual
probe
In line turbidity probe
Required chlorine
dioxide residual
achieved
Cleaning and disinfection
protocol for respiratory
apparatus; microbiological
monitoring program
Monitoring of cleaning protocol
records
Routine review of
process flow diagram
to identify areas of
concern or stagnation
56
Process step
Water source
Prepare
management
procedures
(example)
Establish
verification and
surveillance
(example)
Develop supporting
programs (example)
Point-of-use filtration
and disinfection
program; possible
treatment for
dissolved solids
Distribution
Removal of deadlegs
where possible
Respiratory apparatus
Isolation of unit and disinfection
of source

Internal audit and external audit (by environmental consultant) to confirm that operational
monitoring and corrective actions are being undertaken as stated in the WSP

Monthly heterotrophic colony counts at the tap and in the source water (to track trends
and changes, rather than as an absolute indicator, and to be undertaken by an
accredited laboratory)

Three-monthly sampling for Legionellae of water in the distribution system and at
the point of use

Respiratory apparatus must be disinfected on a regular daily basis and between every
patient; also, it must be regulated in the hospital infection control plan
Staff training and education; maintenance and calibration
57
Appendix G: Control Measures Implemented During
Outbreaks
Table 6: Summary of the main institutionally-associated outbreaks found in the literature
Source/
reservoir
Type of
institution,
country,
year of
outbreak
Potable water
contaminating
sinks, showers,
decorative
fountains
Veterans
hospital,
USA, 2012
Disinfectant
Copper silver
ionization
Mode of
transmission
Probably
inhalation
Clinical
samples
Not stated
Environmental
Samples
Samples
indicated
widespread
contamination
of the potable
water system
At multiple sites
including the
decorative
fountain,
environmental
strain found
matched the
clinical strain
Concentration of
disinfectant
Factors
contribution to
outbreak
Control measures
recommended
Copper- Silver
concentration
were within the
manufacturers
recommended
levels throughout
the water system
Construction
work at the
hospital coincides
with the outbreak.
Construction
likely introduced
organic matter
into the potable
water system
which consumed
the chlorine
residual leading
to Legionella
growth.
Restrict showering,
use point-of-use
filters, turn off
decorative fountain
Improper
sampling
techniques for
Legionella
leading to false
negative results
Remediate potable
water system by
hyperchlorination
and superheating
Use proper
sampling
techniques for
Legionella
Conduct LD
surveillance of
patients
Strive to eradicate
20
Legionella
58
Source/
reservoir
Potable water
contaminating
water faucets
Type of
institution,
country,
year of
outbreak
Hospital
Coronary
and
intensive
care unit,
Slovenia,
1991.
Disinfectant
Not noted
Mode of
transmission
Inhalation
Clinical
samples
Environmental
Samples
L. pneumop
hila
serogroup 1
L. pneumophila
serogroup 1
was isolated
from faucet
water in the
coronary unit
Concentration of
disinfectant
Not noted
Factors
contribution to
outbreak
Hot water source
that was not
adequately
heated (21°-26°C
when turned on
50° - 55°C after 2
minutes)
Control measures
recommended
None given
47
Stagnant water at
the end of a
dead-end pipe
The humidity
level relative to
the distance from
the contaminated
water source was
the most
important risk for
acquiring LD
59
Source/
reservoir
Potable water
contaminating
water faucet
Type of
institution,
country,
year of
outbreak
Hospital
Haematolo
gy unit,
France,
2006
Disinfectant
Municipal
chlorination
Mode of
transmission
Inhalation
suspected
Clinical
samples
Environmental
Samples
Concentration of
disinfectant
Factors
contribution to
outbreak
L. pneumop
hila
Serogroup 5
L. pneumophila
serogroup 5
isolates from
the cold
washbasin
water matched
the patient’s
isolate
Routine
hyperchlorination
checks were
higher than 3
mg/L
Inadequate
temperature
protection
between hot and
cold water which
were close
together
Stagnant water in
the washbasin
thermostatic
mixing valve
Control measures
recommended
Wash basin water
use forbidden until
point-of-use filters
were added
Elimination of
stagnant water by
changing the mixing
valve
Continuous
chlorinator installed
with a target
concentration of
1mg/L
Removal of flexible
44
shower hoses
Potable water
contaminating
shower
Hospital,
USA, 1985
- 1988
Not noted
Inhalation
L. pneumop
hila
serogroup 1
L. pneumophila
serogroup 1
Not noted
Showering with
contaminated
shower heads
during
hospitalization
placed
susceptible
patients at an
increased risk for
acquiring LD
The temperature of
hot water heaters
was raised to
greater than 70°C
for 3 hours, and
each faucet and
shower head was
flushed with
superheated water
for 10 minutes.
A chlorine injector
was installed and
the concentration of
residual chlorine
was maintained at
43
1.5 to 2 mg/L
60
Source/
reservoir
Potable water
contaminating
water heater,
faucets and
showers
Type of
institution,
country,
year of
outbreak
Residential
building for
the elderly
(2
apartment
buildings),
USA, 2009
Disinfectant
Municipal
chlorination
Mode of
transmission
Inhalation
Clinical
samples
Environmental
Samples
Concentration of
disinfectant
Factors
contribution to
outbreak
L. pneumop
hila
serogroup 1
L. pneumophila
serogroup 1
isolated from
numerous
potable water
sources from
the two
apartment
buildings
matched the
clinical strain
Chlorine
disinfection was
not detected at
the point of use in
any of the
residences’
apartments
Free chlorine
residual was not
detected in any
bulk samples
collected from
showerheads or
sink faucets
Hot water
temperatures
were generally
within the ideal
range for
Legionella
amplification
The potable
water system was
colonized with a
virulent strain of
L. pneumophila
Potable water
contaminating
faucets and
showers
Long term
care (2
buildings),
USA, 19951997
Municipal
chlorination
Semiinstantaneou
s hot water
heaters
Not noted
L.
pneumophil
a serogroup
1
L. pneumophila
serogroup 1
isolated from
numerous
potable water
samples from
the two
buildings
matched the
clinical strain
Not noted
Semiinstantaneous hot
water heaters
neither prevented
or controlled
Legionella
colonization
Control measures
recommended
Develop a
Legionella
prevention plan
Remediate using
chlorine based
disinfectant
Permanent
elevation of the
water temperature
(>54.5°C) - ensure
safeguarding
against scalding
Bathing in tub
instead of
showering
Conduct LD
surveillance of
37
residence
Super heating was
unsuccessful
because of anti scald thermostatic
mixing valves
Copper -silver
ionization installed
in both building one
was successful in
controlling
Legionella and one
24
was not
61
Source/
reservoir
Type of
institution,
country,
year of
outbreak
Disinfectant
Mode of
transmission
Clinical
samples
Environmental
Samples
Concentration of
disinfectant
Factors
contribution to
outbreak
Control measures
recommended
Potable water
contaminating
faucets and
showers
Nursing
homes,
Slovenia,
2010
Not noted
Not noted
L.
pneumophil
a serogroup
1
L. pneumophila
serogroup 1
from the clinical
samples and
from the
environmental
water samples
were identical
Not noted
Dead end leading
to stagnation,
inappropriate
temperature and
disinfectant
levels, buildup of
lime scale
Thermal and
chemical
disinfection and
maintaining an
appropriate water
temperature (above
55°C for warm
water and below
20°C for cold
46
water)
Hydrostatic
shock
absorbers
Hospital,
Canada,
1983,
1988-1989
Chlorine
Not noted
L.
pneumophil
a, serogroup
1
L.
pneumophila,
serogroup 1
Not noted
Shock absorbers
Hot water tank were
flushed at 80°C and
faucets were
flushed for 10
minutes with this
heated water.
Additional chlorine
was introduced into
the system to
achieve a free
chlorine residual
level of 15 − 20 ppm
62
Source/
reservoir
Cold-water
distribution
system
Type of
institution,
country,
year of
outbreak
Hospital
paediatric
oncology
ward,
Sweden,
2004
Disinfectant
Not noted
Mode of
transmission
inhalation or
microaspiration of
contaminated
water
Clinical
samples
Environmental
Samples
L.
pneumophil
a, serogroup
1,
L. pneumophila
serogroup 1
identical to that
of the patient
was found in
the hospital’s
cold water but
not in the hot
water
distribution
system.
Concentration of
disinfectant
Not noted
Factors
contribution to
outbreak
Control measures
recommended
Hot water was
mixed with
Legionellacontaminated
cold water
because of openstanding
thermostatic
mixing valves that
were located
some distance
away from the
point of use. A
significant
pressure
difference
between the two
systems
permitted the
entry of hot water
into the cold
water system and
the multiplication
of Legionella. The
temperature of
the cold water
system was 30° 35°C.
All thermostatic hot
and cold water
mixing valves were
replaced.
Water pressure of
the cold water
supply was
increased to just
above that of the
hot water system
resulting in a cold
water temperature
of less <20°C
Thermal flushing of
the cold water
system at 73°C for 1
58
hour.
63
Source/
reservoir
Type of
institution,
country,
year of
outbreak
Cooling towers
located 0.4 km
away
Long-term
care, USA,
2004
Cooling tower
Nursing
home,
Canada,
2005
Disinfectant
Not noted
Not noted
Mode of
transmission
Inhalation
Inhalation
Clinical
samples
Environmental
Samples
L.
pneumophil
a serogroup
1
L.
pneumophila
serogroup 1
found in
samples taken
from the
cooling tower
but not from the
long term care
institution water
supply
Not noted
L. pneumophila
serogroup 1
isolated from
samples taken
from the
nursing home’s
cooling tower.
Not noted
L.
pneumophil
a serogroup
1
Concentration of
disinfectant
Factors
contribution to
outbreak
Control measures
recommended
Weather pattern
Early identification
of aerosol
generating devices
in proximity to
health care
institutions
L. pneumophila
was identified in
the filter of the air
intake suggesting
that the air
intakes provided
a route of entry
for Legionella
Construction at
the hospital
across the street
- construction
dust is known to
be a factor in
Legionella
growth.
Presumptively
shutting down
aerosol generating
devices until the
49
source is identified
Presumptively
shutting down
aerosol generating
devices until the
source was
48
identified
The home’s
ventilation air
intake was next
to the cooling
tower.
64
Source/
reservoir
Potable water
contaminating
ice from an icemaking
machine
Type of
institution,
country,
year of
outbreak
Hospital
Disinfectant
Not noted
orthopedic
ward,
Netherland
s, 2002
Mode of
transmission
Aspiration by
patient with
difficulty
swallowing
Clinical
samples
Environmental
Samples
L.
pneumophil
a serogroup
1
L. pneumophila
serogroup 1
strain from the
ice and from
the patient
were identical
Concentration of
disinfectant
Not noted
Factors
contribution to
outbreak
Control measures
recommended
The water supply
tube was close to
warm (35 °C)
mechanical parts
of the ice
machine
Regular checks for
Legionella and strict
adherence to
maintenance of ice
59
machines
Stagnation in the
water supply line
Legionella
contaminated
water supply line
Potable water
contaminating
ice taken from
an ice-making
machine
Teaching
hospital
Intensive
care unit,
USA, 1994
Chlorination
Aspiration by
patient with
poor gag
reflexes
L.
pneumophil
a serogroup
6
L. pneumophila
serogroup 6
was isolated
from ice and
cold water from
the ice machine
Not noted
Temperature
inside cabinets of
ice machine
averaged 39°C
Replace ice
machine and shock
14
chlorination
Cold water line
was subjected to
heat generated
from within the
ice machines.
65
Source/
reservoir
Type of
institution,
country,
year of
outbreak
Potable water
contaminating
ice from an icemaking
machine which
subsequently
contaminated
bronchoscopes
Hospital,
USA, 2007
Potable water
contaminating
ice from an icemaking
machine which
subsequently
contaminated
bronchoscopes
Medical
centre,
USA, 2008
Disinfectant
Not noted
Chlorine
augmented
by coppersilver
ionization
Mode of
transmission
Clinical
samples
Environmental
Samples
Contaminate
bronchoscope
introducing
Legionella into
the lungs
L.
pneumophil
a serogroup
8
Ice from the ice
machine was
positive for
L. pneumophila
serogroup 8
which
genetically
matched the
strain found in
the patients’
clinical isolates
Not noted
L pneumophila
serogroup 8
from Ice taken
from the ice
machine
matched the
strain found in
the patients’
clinical isolates
No free chlorine
residual
Contaminate
bronchoscope
introducing
Legionella into
the lungs
L. pneumop
hila
serogroup 8
Concentration of
disinfectant
Factors
contribution to
outbreak
Control measures
recommended
Immersing
uncapped sterile
saline solution
directly into in
contaminated ice
baths. This saline
was used to flush
the
bronchoscope.
Ice machine was
removed and
disinfected, and the
inlet water filter
15
replaced
Ice machine not
maintained
Using non-sterile
ice to cool sterile
saline solution
used for flushing
bronchoscope
Contaminated ice
machines were
disassembled,
disinfected and filter
replaced
Chlorine injected
into the cold water
system and the
auto-chlorination
system was reset to
a level of 1.5–2.0
ppm
Saline bottles
refrigerated instead
28
of using ice
66
Source/
reservoir
Potable water
contaminating
Endoscopes
Potable water
contaminating
feeding
solutions
administered
by nasogastric
feeding tube
Type of
institution,
country,
year of
outbreak
Hospital,
France,
2000
Hospital
Intensive
care unit,
USA, 1992
Disinfectant
chlorination
Not noted
Mode of
transmission
Aspiration
Aspiration
Clinical
samples
Environmental
Samples
L.
pneumophil
a serogroup
8
L. pneumophila
serogroup 8
isolated from
contaminated
water was
almost identical
to the patients’
clinical isolates
Inadequate
(concentration
not noted)
L. pneumophila
serogroup 6
from the hot
water matched
the patients'
clinical isolates
Not noted
L.
pneumophil
a serogroup
6
Concentration of
disinfectant
Factors
contribution to
outbreak
Using
contaminated
water to rinse
endoscope
Control measures
recommended
Improving
chlorination
Using central
sterilization for
disinfecting
endoscopes
Using sterile water
for rising
50
endoscopes
Inadequate water
temperature
Complex piping
system
contributing
inadequate
temperature
Hot water
temperature
maintained at 50°C
to 60°C at the
faucets
Sterile water used
for feeding
52
solutions
67
Source/
reservoir
Potable water
contaminating
cold mist
humidifier
Type of
institution,
country,
year of
outbreak
Hospital
Neonatal
care unit,
Cyprus,
2008
Disinfectant
Not noted
Mode of
transmission
Clinical
samples
Environmental
Samples
The neonates
were probably
infected by
inhaling
aerosol
generated by
the cold-mist
humidifier that
was filled with
contaminated
water from the
nursery’s
water taps
L.
pneumophil
a serogroup
3 and
L. pneumop
hila
serogroup 1
L. pneumophila
serogroup 3
strain and
pneumophila
serogroup 1
strain isolate
from
environmental
samples
matched the in
patients’ clinical
isolates
Concentration of
disinfectant
Not noted
Factors
contribution to
outbreak
The humidifier
manufacturer
noted that tap
water could be
used for mist
creation
Control measures
recommended
The 2003 CDC
guidelines advise
against the use of
large-volume, roomair humidifiers that
create aerosols in
hospitals unless
they can be
sterilized or
subjected to highlevel disinfection on
a daily basis and
filled only with
sterile water
Recommended that
the use of
humidifiers in
nurseries be
avoided as the risk
of disseminating
Legionella to large
numbers of
neonates is
54
particularly high
68
Source/
reservoir
Type of
institution,
country,
year of
outbreak
Disinfectant
Mode of
transmission
Clinical
samples
Environmental
Samples
Concentration of
disinfectant
Factors
contribution to
outbreak
Control measures
recommended
Reusable
oxygen
Humidifier
Hospital,
Spain,
2007 −
2008
No cleaning,
disinfection,
rinsing and
drying were
performed
L.
pneumophila
was probably
transmitted to
patients by a
contaminated
oxygen
humidifier via
inhalation
L.
pneumophil
a serogroup
1
Sample from
oxygen
humidifier
tested positive
L. pneumonia
Not applicable
The incomplete
cleaning and
disinfection of
Reusable oxygen
humidifier
probably created
a reservoir for
L. pneumophila
and facilitated
transmission
Recommended the
use of disposable
53
oxygen humidifiers
Potable water
contaminating
nebulizer
Community
hospital,
USA, 1984
− 1988
Not noted
Patients with
chronic
obstructive
lung disease
were probably
infected by
inhaling
aerosol
generated by
a medical
nebulizer that
was washed
with
contaminated
tap water
L.
pneumophil
a serogroup
3
L. pneumophila
serogroup 3
was isolated
from the
hospital water
system.
Not noted
Rinsing the
nebulizer
chamber with tap
water
contaminated
with Legionella
may have
deposited
bacteria in the
chamber,
resulting in their
transmission by
aerosolization to
susceptible
patients during
subsequent use
A combination of
superheating and
hyperchlorination
followed by
intermittent
chlorination to
control but not
eliminate Legionella
L. pneumophila
serogroup 3 in
respirable size
(<5 µm)
droplets was
isolated from
aerosols
generated by
the nebulizer
The use of sterile
fluids in medical
55
nebulizers
69
Source/
reservoir
Decorative
fountain
Type of
institution,
country,
year of
outbreak
Hospital
Cancer
clinic, USA,
2010
Disinfectant
Copper-silver
ionization
supplemental
to
chlorination
Mode of
transmission
Inhalation
Clinical
samples
Environmental
Samples
L.
pneumophil
a serogroup
1
L. pneumophila
serogroup 1
was isolated
from several
sample taken
from different
areas of the
fountain
(sponge like
foam, fountain
filter housing,
fountain trough,
and water
recirculation
system)
Concentration of
disinfectant
Not noted
Factors
contribution to
outbreak
Control measures
recommended
Foam bed that
supported the
decorative rocks
was heavily
contaminated
Fountain was
presumptively shut
down pending
environmental test
results
Use of floodlights
and the electric
fireplace may
have warmed
fountain water
Health care
institutions should
follow current health
care institution
construction
guidelines, which
recommend
fountains not be
installed within any
enclosed spaces in
health
13
environments
70
Source/
reservoir
Potable water
contaminating
birthing pool
water
Physiotherapy
Pool
Type of
institution,
country,
year of
outbreak
Hospital,
Italy, 1999
Hospital,
Canada,
1985 − 1986
Disinfectant
Not noted
Not noted
Mode of
transmission
Clinical
samples
Environmental
Samples
Concentration of
disinfectant
The fact that the
pool water for
water birthing
was
contaminated by
the same
L. pneumophila
serogroup 1 that
was responsible
for the
newborn's
infection
strongly
suggests that
the infection
was acquired
after a
prolonged
delivery in
contaminated
water, perhaps
by means of
aspiration.
L.
pneumophila
serogroup 1
L. pneumophila
serogroup 1 was
isolated from
hospital and pool
water
Not noted
Not noted
L.
pneumophila
serogroup 1
L. pneumophila
identified in
physiotherapy
pool water
Not noted
Factors
contribution to
outbreak
Control measures
recommended
Birthing pool water
contaminated with
Legionella
Pediatricians
(midwives) should be
aware of this possible
transmission route.
When water birth is
practiced, infection
control policies (pool
maintenance and
decontamination for
Legionella species)
are highly
recommended to
prevent Legionella
56
transmission
Not noted
Hospital institutions
with physiotherapy
pool should be
continuously
60
monitored
71
Appendix H: Stakeholders
Stakeholders
Boards of Health (BOH)
Responsibility




Identify and investigate cases/clusters/outbreaks
of Legionella
Conduct source investigation to decrease the risk
to those in institutions
Support institutions by providing information on
how to decrease the risk of health careassociated Legionella
Verify institution has implemented remediation
and control measures (hired an environmental
consultant)
Ministry of Labour (MOL)

Set, communicate and enforce the Occupational
Health and Safety Act and its regulations, for
employers to ensure workers are protected from
health hazards (e.g., Legionella)
Ministry of Municipal Affairs and
Housing (MMAH)

Responsibility for the Building Code Act, S.O.
1992 and Ontario Building Code, including
plumbing
Ministry of Health and Long-Term
Care (MOHLTC)

Provide support to BOH and coordination of
program delivery, communications, information
and documentation
Public Health Ontario (PHO)

Provide expert advice and/or support to BOH
Public Health Ontario Laboratories
(PHOL)

Provide timely and comprehensive lab support to
PHUs so PHUs can fulfill their responsibilities
above
72
Stakeholders
Ministry of the Environment and
Climate Change (MOECC)
Responsibility



Owners and operators of health
care institutions



Develop policies, legislation, regulations and
standards related to the environment, drinking
water and drinking water systems
Enforcement of environmental laws
Monitoring and reporting to track environmental
progress
Owners of health care institutions to have staff
responsible for managing maintenance services
and for checking and maintaining water systems;
keeping records
Owners must have a plan for remediation and
emergency control measures in the event of an
LD outbreak
Surveillance/monitoring of cases of Legionella
and report to BOH
73
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