Download Transmission Based Precautions

Transmission Based Precautions – Literature Reviews
Droplet Precautions
April 2008
Search Strategy – Droplet Precautions
PRINCIPAL RESEARCH QUESTION/OBJECTIVE:
What precautions can be taken to ensure patients / healthcare workers / visitors safety, from droplets which are
disseminated during healthcare procedures or human activities?
Search strategy for identification of studies
Key Questions
1.
What activities (including healthcare procedures and human activities e.g. coughing etc) can cause
droplets to be disseminated from the respiratory tract?
2.
What precautions can be taken to ensure patients / healthcare workers / visitors safety, from droplets which
are disseminated during healthcare procedures or human activities?
3.
What microorganisms are disseminated via droplets from infected / colonised patients with the potential to
cause cross-transmission and cross-infection in patients / healthcare workers / visitors?
4.
What type of environment(s) should be used to deliver care to patients with infections that can be
disseminated via droplets?
The recommendations and “Droplet Precautions – a systematic review of the evidence” are based on a collation of
review and critical appraisal of the scientific evidence identified by search strategies carried out using the above
key questions.
Further details on each search strategy and results can be supplied on request.
Period of publication
Strategy key words
(Full search strategies available
on request)
Electronic databases
(tick as appropriate)
1997-2007
Droplet$
Precaution$
Patient$
Healthcare worker$
Visitor$
Healthcare
Personal protective equipment
Patient placement
Ventilation
Isolation
Environment$
Patients’ rooms
Care
Infection
Coughing
Delivery of healthcare
MEDLINE
Science Direct
CINAHL
Cochrane Library
British Nursing Index
Disease transmission
Nebulization
Bacteria
Viruses
Respiratory tract infections
Bacterial infections
Virus diseases
Disease reservoirs
Fungi
Sneezing
Speaking
Intubation
Nasopharyngeal aspiration
Respiratory tract infections
Nebulisation
X
X
X
X
PsycINFO
EMBASE
SIGLE
Web of Science
1
Additional Resources
(tick as appropriate)
Websites
(tick as appropriate)
How many papers found
How many papers included
How many papers excluded
References checked for relevant articles
X
Review of abstracts of professional meetings/ conferences
Personal libraries consulted
Experts consulted (give details if applicable)
Handsearching of journals (name relevant journals e.g. Journal
of Hospital Infection, Infection Control and Hospital
Epidemiology)
CDC
X
WHO
Department of Health
X
Scottish Government
HPA
X
Scottish Government Health Dept.
324
27
297
X
X
X
ii) Selection criteria for inclusion of studies
Sample
All health and social care workers.
Outcome measure(s)
Interventions to minimise the spread of infections by droplets.
Other inclusion criteria
Any study or guidance document not reviewed within the CDC Guideline for Isolation
Precautions: Preventing Transmission of Infectious Agents in Healthcare Settings 2007
Language Limitations
English language only
iii) Quality assessment
Study quality assessment
The newly published CDC Guideline for Isolation Precautions: Preventing Transmission of Infectious Agents in Healthcare
Settings 2007, (Siegel et al., 2007) has been evaluated by five independent reviewers using the AGREE instrument (The
AGREE Collaboration, 2001) which is designed to assess the methodological quality of guidelines. The results show the
guidelines suitable for adaptation as the primary reference source for literature review and formulation of recommendations.
A literature search was conducted using HPS ICT search strategies, based on agreed research questions. Identified studies, not
already reviewed within the CDC guidelines, were assessed for relevance and critically appraised using SIGN-50
methodology (SIGN, 2004) to determine if additional information or considerations were required for production of
transmission based precautions for healthcare settings in NHS Scotland.
The methodology for grading the supporting evidence is found on the Evidence Tables including Considered Judgment
Section and available from the HPS Infection Control Team on request.
Category of Recommendation
The recommendations have been categorised based on a combination of the system used in the CDC/HICPAC (Siegel et al.,
2007) and EPIC 2 National Evidence-Based Guidelines for Preventing Healthcare-Associated Infections in NHS Hospitals in
England
Category IA - Strongly recommended for implementation and strongly supported by well-designed experimental, clinical, or
epidemiologic studies.
Category IB - Strongly recommended for implementation and supported by some experimental, clinical, or epidemiologic
studies and a strong theoretical rationale.
Category IC - Mandatory or required for implementation
Category II - Suggested for implementation and supported by suggestive clinical or epidemiologic studies or a theoretical
rationale.
GPP (Good Practice Point) – Is a recommendation for best practice based on the expert opinion or practical experience of
the Model Policies Steering Group
No recommendation; unresolved issue. Practices for which insufficient evidence or no consensus regarding efficacy exists.
2
Data collation and analysis
The SIGN 50 methodology including reviewing templates are available from the SIGN website (http://www.sign.ac.uk)
The AGREE Instrument which is used for assessment and evaluation of the quality of evidence-based guidelines can be found
at www.agreecollaboration.org
REVIEW STATUS
(delete as appropriate)
DATE ISSUED
REVIEW DATE
CONTACT PERSON
Ongoing/Complete
April 2008
April 2011
Heather Murdoch
3
Table of Contents
Search Strategy – Droplet Precautions .................................................................................................... 1
1
Recommendations – Droplet Precautions........................................................................................ 5
1.1
Standard Infection Control Precautions (SICP)....................................................................... 5
1.2
General principles of Transmission Based Precautions........................................................... 5
1.3
Droplet Precautions.................................................................................................................. 5
1.4
Patient Placement..................................................................................................................... 5
1.5
Personal Protective Equipment ................................................................................................ 6
1.6
Additional Precautions - potentially aerosol generating procedures ....................................... 7
1.7
Patient Transport...................................................................................................................... 7
1.8
Respiratory Hygiene/Cough Etiquette ..................................................................................... 7
2
Practical Application........................................................................................................................ 7
3
Resource Implications...................................................................................................................... 7
4
Droplet Precautions – a systematic review of the evidence............................................................. 8
General Principles of Transmission Based Precautions....................................................................... 8
Droplet Transmission........................................................................................................................... 8
Infectious agents transmissible by droplets ....................................................................................... 10
4.1
Epidemiologically important organisms ................................................................................ 10
4.2
Potential Agents of Bioterrorism ........................................................................................... 11
Droplet Precautions............................................................................................................................ 11
4.1
Spatial Separation .................................................................................................................. 11
4.2
Respiratory Hygiene / Cough Etiquette ................................................................................. 12
4.3
Hand Hygiene ........................................................................................................................ 13
4.4
Personal Protective Equipment .............................................................................................. 13
4.5
Patient Placement................................................................................................................... 15
4.6
Additional considerations ...................................................................................................... 15
Implementation of Droplet Precautions ............................................................................................. 15
Identification of Infectious Disease ................................................................................................... 15
5
Conclusions.................................................................................................................................... 16
5.1
General Principles of Transmission Based Precautions......................................................... 16
5.2
Droplet Transmission............................................................................................................. 16
5.3
Pathogens transmissible by droplets ...................................................................................... 17
5.4
Epidemiologically important organisms ................................................................................ 17
5.5
Potential Agents of Bioterrorism ........................................................................................... 17
Droplet Precautions............................................................................................................................ 18
5.6
Spatial Separation .................................................................................................................. 18
5.7
Respiratory Hygiene / Cough Etiquette ................................................................................. 18
5.8
Hand Hygiene ........................................................................................................................ 19
5.9
Personal Protective Equipment .............................................................................................. 19
5.10 Additional Precautions - aerosol generating procedures ....................................................... 20
5.11 Patient Placement................................................................................................................... 20
6
References...................................................................................................................................... 20
4
1
Recommendations – Droplet Precautions
Caveat
Transmission based precautions are designed to be an adjunct to standard infection control
precautions. It is therefore stressed that the nine elements of standard infection control precautions
must underpin all health and social care activities. It is therefore assumed for the purpose of this
literature review that all standard infection control precautions are being adhered to and therefore do
not require specifically addressed within this literature review and associated recommendations.
More information on the standard infection control precautions including associated literature reviews
is available from the Model Infection Control Policies website:
http://www.hps.scot.nhs.uk/haiic/ic/modelinfectioncontrolpolicies.aspx
1.1
1.1.1
1.2
Standard Infection Control Precautions (SICP)
Standard Infection Control Precautions should be adhered to for all health and social care
activities. (Category 1A)
General principles of Transmission Based Precautions
1.2.1
Transmission based precautions should be implemented for treatment of patients with
suspected or confirmed infection which is potentially highly transmissible or as a result of a
considered epidemiologically important organism. (Category 1A) (see Appendix 1 in policy)
1.2.2
The duration of transmission based precautions should be lengthened for immunosuppressed
patients due to the risk of protracted shedding of viruses to avoid cross transmission. (Category
1A)
1.3
Droplet Precautions
1.3.1
Droplet precautions should be applied for patients with respiratory infections known or
suspected to be transmissible by droplets (defined as >5μM) that can be generated by human
activities such as sneezing and coughing as recommended in Appendix 1 in policy. (Category
1B)
1.3.2
Droplet precautions should be continued until cessation of symptoms or according to specific
advice relevant to the causative organism. (see Appendix 1 in policy) (Category 1B)
1.4
Patient Placement
1.4.1
Patients with respiratory infections requiring droplet precautions should be placed in single
rooms when possible. (Category II)
1.4.2
If single rooms are unavailable, cohorting should be considered based on the placing together
patients with the same infection if appropriate. (Category 1B)
5
1.4.3
Patients with excessive respiratory symptoms such as coughing or production of respiratory
secretions should preferentially be placed in a single room. (Category II)
1.4.4
If cohorting options with patients with same respiratory infections are not available avoid
placing patients on droplet precautions with immunocompromised patients or long stay
patients. (Category II)
1.4.5 Local infection control teams should be consulted for advice on individual risk assessments on
patient placement decisions. (Category II)
1.4.6
Patients should be separated by at least 3 feet from each other and bed curtains can be drawn as
an additional physical barrier. (Category 1B)
1.4.7
PPE must be changed and hand hygiene performed between contact with different patients on
droplet precautions within the same room, even if cohorted with same respiratory infection.
(Category 1B)
1.4.8
Decisions on patient placement within community settings should be individually risk assessed
based on potential infection risks to other patients. (Category II)
1.4.9
Patients showing symptoms of respiratory infections requiring droplet precautions should be
separated into a room or cubicle as soon as practical and given instruction on respiratory
hygiene / cough etiquette precautions. (Category II)
1.5
Personal Protective Equipment
1.5.1
A surgical mask should be donned before entry into room or cubicle with patients on droplet
precautions. (Category 1B)
1.5.2
The CDC guidelines and additional searched literature, do not contain specific guidance on the
routine wearing of eye protection in addition to mask when working within 3 feet of patients
on droplet precautions. (Unresolved Issue)
1.5.3
Certain respiratory diseases such as outbreaks of pandemic influenza or SARS have separate
sources of infection control and transmission based precautions information which should be
referred to:
SARS
http://www.hps.scot.nhs.uk/resp/severeacuterespiratorysyndrome-sars.aspx?subjectid=121
http://www.hpa.org.uk/infections/topics_az/SARS/menu.htm
http://www.who.int/csr/sars/en
Influenza
http://www.hps.scot.nhs.uk/resp/influenza.aspx?subjectid=95
http://www.hpa.org.uk/infections/topics_az/influenza
http://www.who.int/csr/disease/influenza/en
6
1.6
1.6.1
1.7
Additional Precautions - potentially aerosol generating procedures
The use of suitable fit tested FFP3 respirators are required in addition to gowns, gloves and eye
protection for carrying out aerosol generating procedures (e.g. intubation) on patients suffering
from for example SARS. (Category II)
Patient Transport
1.7.1
It is recommended that patients requiring use of droplet precautions within acute and
community settings should not be moved unless necessary requirement to do so, e.g. for
medical reasons. (Category II)
1.7.2
If it is necessary to move a patient on droplet precautions, the patient should be instructed on
respiratory hygiene / cough etiquette and requested to wear a surgical mask if possible.
(Category 1B)
1.8
Respiratory Hygiene/Cough Etiquette
1.8.1
All healthcare workers should receive specific instruction on the importance of droplet
precautions for the prevention and control of transmission of infections via respiratory droplets
particularly during outbreaks. (e.g. of influenza, etc) (Category 1B)
1.8.2
The duration of droplet precautions may require to be extended for specific patient populations
e.g. immunosuppressed patients, due to the pattern of prolonged virus shedding. (Category 1A)
A full description of the criteria used to determine if additional precautions are required are included
in Appendix 1 in the policy.
2
Practical Application
As the use of droplet precautions has been recommended for some time, therefore no significant
change to practice should be required, however, the standards set down must be achieved.
3
Resource Implications
As per current policies. All resources required for implementing droplet precautions should already be
in place.
7
4
Droplet Precautions – a systematic review of the evidence
Caveat
Transmission based precautions are designed to be an adjunct to standard infection control
precautions. It is therefore stressed that the nine elements of standard infection control precautions
must underpin all health and social care activities. It is therefore assumed for the purpose of this
literature review that all standard infection control precautions are being adhered to and therefore do
not require specifically addressed within this literature review and associated recommendations.
More information on the standard infection control precautions including associated literature reviews
is available from the Model Infection Control Policies website:
http://www.hps.scot.nhs.uk/haiic/ic/modelinfectioncontrolpolicies.aspx
General Principles of Transmission Based Precautions
Transmission Based Precautions are a set of precautions which can be implemented when patients are
either suspected or known to be infected with potentially transmissible infectious agents. The
precautions are defined and grouped according to route of transmission of the particular causative
infectious agent. A judgment on which transmission based precautions are required is based on clinical
symptoms or information on known outbreaks and any precautions applied can be altered when
additional information is acquired i.e. on specific identification of particular infectious agent or
regarding mode of transmission (Siegel et al., 2007) (See Appendix 1 in policy).
Transmission Based Precautions should be implemented based on available clinical knowledge, while
awaiting actual identification of the causative agent and should be continued either for the duration of
illness or while still a risk of transmission. The duration that transmission based precautions should be
continued depends on a number of factors such as patient group affected i.e. immuno-suppressed
patients may required a greater duration of precautions due increased length of viral shedding etc.
(Siegel et al., 2007) (See Appendix 1 in policy).
Droplet Transmission
Droplet transmission is defined as the transfer of large particle droplets (>5µm) from an infected
respiratory tract directly to a mucosal surface or conjunctivae of another individual over a short
distance. Due to the comparative large size of the particles it is accepted that droplets only travel
relatively short distances through the air (Siegel et al., 2007, Collignon and Carnie, 2006, SEHD and
HPS, 2005).
Review of scientific evidence and available guidance has shown that infected individuals can cause
respiratory droplets to be generated as a result of a number of human activities such as coughing,
sneezing and even talking (Siegel et al., 2007, DH, 2007b, SEHD and HPS, 2005).
A number of studies have been conducted which have confirmed transmission of microorganisms via
droplets and these have been extensively reviewed within the CDC Guidelines. Studies have shown
that the mucosal surfaces of the nose, eyes and occasionally the mouth are potential routes of entry to
susceptible hosts by respiratory microorganisms (Siegel et al., 2007).
Extensive review of scientific literature has been carried out to ascertain the maximum distance that
droplets can be transmitted and this issue is to some extent unresolved. However a number of studies
have shown that droplets are transmitted over short distances and this has been historically defined as
8
less than 3 feet from the patient. This distance has been used as a measure of when precautions such as
use of surgical masks are required and this has been shown to be effective in prevention of
transmission of microorganism via this route (Siegel et al., 2007).
One small study (Ng et al., 1999) showed that visible and actual spread of respiratory droplets
scattered over a distance of up to 168cm which is greater than the 3 feet limit usually considered as a
sufficient distance barrier to negate requirement for droplet precautions.
The distance that droplets can travel from infected respiratory tracts depends on a number of factors
including, the speed, size, density and a number of additional environmental factors such as
temperature, humidity etc. In addition, the activity, which resulted in the droplet expulsion from the
respiratory tract, affects this distance of spread and therefore has to be considered when deciding on
precautions required (Siegel et al., 2007, Collignon and Carnie, 2006).
Studies show that infections transmittable via this route include the influenza virus, rhinovirus,
adenovirus, Group A streptococcus and SARS- CoV (Siegel et al., 2007). Occasionally, pathogenic
organisms, which are not normally transmitted via the droplet route such as Staphylococcus aureus
have been shown to transmit from the respiratory tract and this, may need considered in an outbreak
situation (Siegel et al., 2007).
Certain healthcare procedures such as intubation, nasopharyngeal aspiration, tracheostomy care, chest
physiotherapy, bronchoscopy and nebuliser therapy can cause aerosolisation of microorganisms,
which usually transmit via the droplet route and therefore may require additional precautions. This has
been implicated in cases of nosocomial transmission of infectious agents such as SARS- CoV to
healthcare workers (Siegel et al., 2007, DH, 2007b, HPA, 2006, HPA, 2005, SEHD and HPS, 2005,
WHO, 2004).
A number of articles and studies were published as a result of the SARS outbreak and although most
of the studies were relatively small scale due to the nature of the outbreak, a number of interesting
points have been identified. One scientific study (Christian et al., 2004) described a failure of PPE
which resulted in cross transmission of SARS to healthcare workers. Although this was not a
controlled study it highlighted that none of the N95 respirators had been fit tested prior to carrying out
aerosol generating procedures. This therefore adds to the evidence that respiratory infections
transmissible via droplets can be aerosolised during certain healthcare procedures and may therefore
require additional precautions, which should be properly applied.
It is also noted in some studies and guidance that medical conditions such as asthma, allergic rhinitis
and chronic obstructive lung disease may result in droplets from respiratory tract transmitting short
distances into the immediate environment and although these patients may not be infectious,
precautions should be taken (Siegel et al., 2007).
Infectious agents that result in HAI are mainly from human sources although occasionally are
environmental. Human sources of infection include patients but also visitors, families and healthcare
workers. This can include people with active and obvious respiratory infections; those with unknown
asymptomatic infections and those colonised with pathogens which are transmissible via respiratory
droplets (Siegel et al., 2007).
Patients in hospital or other healthcare facilities can be particularly vulnerable to infection as a result
of other medical conditions and this can influence the severity of disease resulting from healthcare
HAI. Certain patient populations are considered high risk such as immuno-compromised individuals,
patients in ITU and Burns units etc and this should be considered when assessing potential risk posed
by microorganisms which disseminate via respiratory droplets (Siegel et al., 2007).
9
The mode of transmission of microorganisms varies and there are several classes of pathogenic
organisms that can disseminate via respiratory droplets. It is also reported that some pathogens can
transmit by more than one route (Siegel et al., 2007).
Infectious agents transmissible by droplets
The new CDC Isolation Guidelines (Siegel et al., 2007) include a substantial literature review with
supporting evidence, of the main pathogens transmissible by the droplet route. Microorganisms which
are transmissible by this route include Bordetella pertussis, influenza virus, adenovirus, rhinovirus,
Mycoplasma pneumoniae, SARS-associated coronavirus (SARS-CoV), group A streptococcus,
mumps, Parvovirus, rubella and Neisseria meningitidis. Additionally there is some evidence that
respiratory syncytial virus (RSV) is transmissible via droplets although the reviewed studies suggest
that it is direct contact with the respiratory droplets which is the most important route of transmission
of this infection (Siegel et al., 2007, Banning, 2006).
In a retrospective cohort study (Gerber et al., 2001), the authors show that adenovirus has the potential
to be transmitted via droplets when it presents as a respiratory infection, however it is noted that
adherence to droplet and contact precautions is effective and control spread. The authors also stress the
importance of swift diagnosis to ensure that the correct precautions are in place.
One recently published review article (Tellier, 2006) argues that aerosol transmission of influenza A is
an underestimated mode of transmission. However although interesting, this literature review has not
been conducted with sufficient rigour to provide additional evidence for use in formulation of
recommendations for the transmission based precautions. The findings reported within another
recently published literature review, which demonstrates a rigorous approach to assessment of
evidence, indicates however that influenza transmission is primarily via the droplet route and that the
airborne route is not frequent enough to be considered a concern (Brankston et al., 2007).
Occasionally, scientific evidence indicates that some microorganisms that are not commonly
transmitted by the droplet route can be disseminated in this way. There are published studies which
demonstrate the organism S. aureus being disseminated by droplets from the nose in both experimental
and clinical situations, however this is generally quite rare (Siegel et al., 2007).
A study (Kimura et al., 1999) showed that there was a significantly higher risk of Helicobacter pylori
amongst patients residing in care homes compared to home care and that this implies the possibility of
droplet spread. This paper is interesting but there is not sufficient evidence for inclusion in
transmission based precautions unless further studies are published to substantiate this.
In addition to the list of pathogens (See Appendix 1 in policy) known to be transmissible via droplets,
there have been new and emerging diseases that have been shown to transmit via this route e.g. SARS
and avian influenza. (Siegel et al., 2007, DH, 2007b, DH, 2007a, HPA, 2006, WHO, 2006b, WHO,
2006a). Additionally, evidence contained within a retrospective cohort study demonstrated high levels
of SARS-CoV virus present in saliva and throat wash, which supports the transmission of SARS by
oral droplets. However, the authors detected the presence of virus in cell free form and hypothesised
that this could provide a possible explanation to support the potential for a degree of airborne spread
(Wang et al., 2004).
4.1
Epidemiologically important organisms
There is a growing list of microorganisms which are considered to epidemiologically important. This
term encompasses pathogenic organisms, which can cause outbreaks within healthcare settings,
10
requiring additional methods of infection prevention and control. A number of these organisms are
known to disseminate via the droplet route and include, influenza, group A streptococcus, RSV etc.
The seriousness of HAI caused by any of these pathogens can be increased by the setting , i.e. the
occurrence of Group A strep within a Burns unit, because of the patient population affected and the
comparative severity of illness within these populations. Another feature of epidemiologically
important organisms is that a number are resistant to antibiotics e.g. MRSA, VRE etc. (Siegel et al.,
2007).
4.2
Potential Agents of Bioterrorism
The CDC Isolation guidelines (Siegel et al., 2007) have issued an appendix and additional information
on a range of microorganisms which are potentially associated with acts of bioterrorism. Review of the
scientific literature shows that a number of these organisms are believed to be transmissible via the
droplet route and therefore requiring implementation of droplets precautions as part of the control
strategy. These organisms include Pneumonic Plague and there is some experimental evidence to show
that some viral haemorrhagic fevers i.e. Ebola, may disseminate via droplets a short distance into the
environment and therefore infection control advice for a case of haemorrhagic fever viruses involves
implementation of droplet as well as contact precautions with additional eye protection. However in
the case of a outbreak caused by deliberate release, the advice given in the present guidelines is that
airborne precautions should be used due to the lack of available knowledge about the causative strain.
Droplet Precautions
These are a set of precautions designed to prevent cross transmission of infectious agents, which are
transmissible by respiratory droplets and include the components below.
4.1
Spatial Separation
It is known that droplet spread is dependant on a number of factors such as the method they are
generated (e.g. coughing etc) and even on environmental factors such as temperature and humidity,
however it is accepted that the spread is generally a short distance. Traditionally, an area of 3 feet
around the patient has been considered as the potential zone of spread and the use of this exclusion
zone has been effective in the management of outbreaks of respiratory diseases transmissible via this
route (Siegel et al., 2007, DH, 2007b, SEHD and HPS, 2005, Tablan et al., 2004, WHO and
IFRCRCS, 2001, Collignon and Carnie, 2006).
It was recommended within the previously published “Guideline for isolation precautions in hospitals”
(Garner, 1996) that a distance of 3 feet should be maintained between patients and healthcare workers/
visitors to protect from respiratory illnesses transmissible by large particle droplets generated by
coughing, sneezing etc. It was also recommended within this guidance that healthcare workers should
don a surgical mask when working within this distance from a patient requiring droplet precautions.
However, these guidelines mentioned that locally, healthcare establishments may implement the
wearing of a surgical mask on entering the room of patients infected with respiratory illness
transmissible by droplets, rather than wait until within 3 feet.
A number of recent studies (Ng et al., 1999, Siegel et al., 2007) have shown that a spatial separation of
3 feet may be sufficient in most occasions however there is some evidence that some droplets may
travel further dependant on a number of different factors such as environmental conditions, method
causing generation of respiratory droplets etc. Additionally on review of recently published studies
particularly as a result of the SARS outbreak, there was a suggestion that droplets could potentially
11
spread as far as 6 feet from the source and this appeared to have resulted in nosocomial transmission to
healthcare workers performing healthcare activities on infected patients.
It is clear from the literature review contained within the current CDC guidance that more studies are
required to elucidate the mode of droplet spread. Based on this literature review, the authors
recommend that surgical masks should be donned within 6 - 10 feet of a patient or on entry to the
patient’s room particularly if exposure to pathogens transmissible by droplets is possible or known
(Siegel et al., 2007).
Therefore, it would seem prudent to recommend that a precautionary distance of 3 feet should not be
as single deciding factor for implementation of droplet precautions such as donning of a surgical mask
and a practical view may need to be adopted i.e. upon entry to the patient’s room. This may be
particularly sensible when dealing with newly emerging diseases of relatively unknown etiology
(Siegel et al., 2007, WHO, 2004).
The current review of the scientific literature, which shows that maintenance of a spatial distance of 3
feet is sufficient to prevent most cases of droplet transmission of microorganisms, and therefore
substantiates inclusion of a recommendation of maintenance of this precautionary distance within
communal waiting areas (Siegel et al., 2007).
Recent scientific evidence included within the review section of the CDC guidance states that
microorganisms transmissible only via the droplet route do not require special air handling, as they do
not remain infective over long distances and this is in line with current droplet precaution guidance
(Tablan et al., 2004, Collignon and Carnie, 2006, SEHD and HPS, 2005, WHO, 2004). Additional
studies specifically on influenza have added weight to the evidence by demonstrating that transmission
to healthcare workers was prevented by implementation of droplet precautions despite the use of
positive pressure rooms which would increase the risk of cross transmission of microorganisms in one
particular healthcare establishment (Siegel et al., 2007).
A number of published studies are concerned with outbreaks of unknown origin and microorganisms
and have shown that often, initially implemented infection control precautions can be excessive,
however can be changed when more is known about the causative organism (Christian et al., 2004).
This can result in infection control precautions altering over time as more information is established.
4.2
Respiratory Hygiene/Cough Etiquette
The importance of swift implementation of infection control precautions was highlighted during the
SARS outbreak as extensive transmission of the disease occurred to patients and staff at the triage
stage or point of entry to healthcare. The importance of a strategy to deal with this has been stressed
and the approach which is recommended is the introduction of respiratory hygiene / cough etiquette as
part of standard infection control precautions and additional transmission based precautions (Siegel et
al., 2007, SEHD and HPS, 2005).
The introduction of respiratory hygiene / cough etiquette is aimed at patients and their families
particularly with undiagnosed respiratory illnesses (coughing, sneezing etc) and is a fundamental
component of droplet precautions. The literature suggests that application of this precaution at the
point of entry into healthcare facilities reduces the transmission of respiratory infections via droplets
(Siegel et al., 2007).To encourage compliance with respiratory hygiene / cough etiquette by healthcare
workers, patients and visitors it is clear that education and training is required and this can be achieved
by use of posters and signs describing these precautions (Siegel et al., 2007).
12
The main components of respiratory hygiene / cough etiquette, contained within the reviewed
scientific literature are; covering the mouth and nose with a disposable tissue when coughing or
sneezing followed by prompt disposal of the tissue in a suitable waste receptacle; use of surgical mask
by the patient if possible; performance of hand hygiene following contact with respiratory secretions
and separation of at least 3 feet between patients / families etc suffering from respiratory infections
within communal areas such as waiting rooms etc if achievable (Siegel et al., 2007, SEHD and HPS,
2005). Furthermore, the CDC guidance states that healthcare workers should not look for fever as an
indication of respiratory illness and respiratory hygiene / cough etiquette precautions should be applied
as a precautionary measure in the absence of the clinical symptom of fever and even when the patient
presents with chronic obstructive lung disease, asthma or other allergic conditions such as allergic
rhinitis (Siegel et al., 2007). A number of scientific studies reviewed within the primary reference
source substantiate the efficacy of this approach for prevention of transmission of infections via
respiratory droplets. However it has been noted that wearing of masks by patients in some healthcare
settings may be difficult and this may have to be considered e.g. paediatrics. (Siegel et al., 2007)
4.3
Hand Hygiene
There are many studies on the role of hand hygiene within infection prevention and control and have
been extensively reviewed and critiqued within the CDC Isolation Guidelines and additional literature
identified from the search. It is clear from the reviews that performance of hand hygiene is vital to
prevent transmission of respiratory infections transmittable via droplets within the healthcare
environment (Siegel et al., 2007, Ng et al., 1999, Collignon and Carnie, 2006). The role of hand
hygiene, including all aspects of the technique has been extensively reviewed within the literature
review for the HPS Model Standard Infection Control Policy and for the subsequent annual review.
The hand hygiene model policy also covers issues such as wearing of artificial nails and jewellery etc
and should be referred to for all aspects of hand hygiene required for the standard infection control
precautions which are required as a baseline for implantation of transmission based precautions (HPS,
2007).
4.4
Personal Protective Equipment
Droplet transmission is defined as respiratory droplets containing infectious agents, which are
transmitted a short distance into the environment directly to the mucosal surface of a recipient.
Therefore one of the main precautions is to prevent access to the mucous membrane by use of Personal
Protective Equipment (PPE). The evidence base would imply that due to the increased risk from
infectious agents spread by droplet, contact and airborne additional PPE must be considered. This
includes that even if the requirement for PPE is in line with SICPs alone it should be donned prior to
entering the patient area or providing care activities in order to minimise the risk of transmission of the
known/suspected infectious agent.
An appendix has been attached to the policy which covers the safe donning and removal of PPE to
avoid contamination.
4.4.1
Gloves
Gloves are not recommended specifically for droplet precautions however they form part of the
baseline standard infection control precautions required to avoid exposure from potentially harmful
microorganisms that may be present in patient’s blood or body fluids such as respiratory secretions
therefore are required for droplet precautions. In addition, a number of infections transmissible by
droplets can also be spread by contact and therefore this potential route of transmission via
13
contaminated surfaces must be considered. The use of gloves is covered in detail within the HPS
model infection control policy on PPE and associated literature reviews (HPS, 2007).
4.4.2
Gowns
The use of gowns has been reviewed within the CDC guidance and within the HPS model policy on
PPE. Specific advice on the use of gowns is recommended as part of standard infection control
precautions to protect from exposure to potentially infected blood and body fluids such as respiratory
excretions. The use of gowns is covered in detail within the HPS model infection control policy on
PPE and associated literature reviews and their use as part of droplet precautions should be governed
by standard infection control precautions. (Siegel et al., 2007, HPS, 2007).
4.4.3
Disposable Surgical Masks
The use of a surgical face mask as PPE for the purpose of droplet precautions is reviewed within the
CDC guidance (Siegel et al., 2007). In addition the HPS model policy and associated literature review
(HPS, 2007) on PPE contains a review on the role of masks, as part of standard infection control
precautions to protect from exposure to infectious agents via splashes or sprays of blood or body fluids
such as respiratory secretions; to protect patients from exposure to potentially pathogenic organisms
carried by the healthcare workers in their nasal cavity and also as part of respiratory hygiene / cough
etiquette and may be used by patients to cover the nose and mouth when coughing to prevent onward
transmission.
The use of surgical masks is reviewed in detail within current guidance documents because exposed
mucosal surfaces of the nose and mouth can provide an easy route of entry to the body for pathogenic
microorganisms. Therefore it is recommended that masks and eye protection be worn for all healthcare
procedures that potentially generate splashes of blood and body fluids (Siegel et al., 2007). In addition,
an extensive review of the scientific and clinical evidence on the protective effect of surgical face
masks has been conducted within the primary reference source. This review has shows the efficacy of
the wearing of surgical face masks by healthcare workers to protect from exposure from potentially
infective respiratory droplets (Siegel et al., 2007).
It has been noted within the published scientific literature that certain procedures such as
bronchoscopy, endotracheal intubation etc can result in the generation of aerosols and therefore
additional precautions will be required to prevent transmission and it is recommended that masks and
eye protection as well as gloves and gown are worn (Siegel et al., 2007).
The CDC guidance (Siegel et al., 2007) contains a review of the efficacy of different mask types,
however no recommendations have been made regarding this issue.
4.4.4
Eye Protection – Goggles and Face Shields
The use of eye protection in addition to droplet precautions has been studied but not extensively. In
fact there are only a couple of scientific reports concerning reduction of occupational transmission of
RSV by the use of eye protection. However, it is not clear from these studies if other factors were
involved such as the prevention of hand to eye contact rather than preventing exposure to respiratory
droplets straight to the eye surface (Siegel et al., 2007).
14
4.5
Patient Placement
In addition to standard infection control precautions and the instigation of droplet precautions, the use
of a single room is preferable for care of patients with respiratory infections transmissible by droplets.
If this option is not possible there are alternatives involving cohorting. This involves clustering of
groups of patients suffering from the same disease, and the use of this method has been reviewed
within recent scientific literature and current guidance (Siegel et al., 2007, Tablan et al., 2004, DH and
CMO, 2003, HPA, 2005, SEHD and HPS, 2005, WHO and IFRCRCS, 2001, WHO, 2004). This type
of approach is particularly relevant in the case of an outbreak e.g. seasonal or pandemic influenza,
where there are potentially high numbers of people affected and requiring healthcare across all
settings. In addition, there are a significant number of studies looking at evidence to support other
options such as the use of spatial barriers such as distance between beds of at least 3 feet and the use of
physical barriers such as bed curtains (Siegel et al., 2007, Ng et al., 1999).
4.6
Additional considerations
There is an extensive review of recent scientific literature and studies, particularly as a result of the
SARS outbreak which indicates that certain procedures for example intubation, nasopharyngeal
aspiration, tracheostomy care, chest physiotherapy, bronchoscopy and nebuliser therapy etc, when
carried out on patients suffering from respiratory illnesses considered transmissible by droplets, can
result in generation of aerosols and therefore additional precautions will be required. The reviews
show that use of suitable fit tested FFP3 respirators are required in addition to gowns, gloves and eye
protection (Siegel et al., 2007, Collignon and Carnie, 2006, DH, 2007b, HPA, 2005, SEHD and HPS,
2005, WHO, 2006a).The literature also shows that there is a higher risk of cross transmission of
respiratory infections to healthcare personnel if they are not adequately trained in the required
infection control precautions or use of PPE (Siegel et al., 2007, Zamora et al., 2006, Christian et al.,
2004).
There is clearly a risk of contamination during the actual process of donning and removing PPE and
this highlights the importance of appropriate training and instruction in the correct techniques.
Implementation of Droplet Precautions
Transmission of infectious respiratory diseases by droplets to patients and healthcare workers within
the community can be contained by implementation of cough and respiratory etiquette and droplet
precautions (Siegel et al., 2007, DH and CMO, 2003, DH, 2007a, HPA, 2006, SEHD and HPS, 2005,
WHO and IFRCRCS, 2001, WHO, 2006a). A number of studies highlight the importance of staff not
attending work when suffering from a respiratory illness and also emphasis the protective effect
offered by staff vaccination against influenza (Siegel et al., 2007, DH, 2006).
Identification of Infectious Disease
To prevent transmission of various infectious diseases across healthcare settings, it is vital that the
disease and causative organism is identified as rapidly as possible to enable the correct transmission
based precautions to be implemented (Siegel et al., 2007, HPA, 2005).
15
5
Conclusions
Caveat
Transmission based precautions are designed to be an adjunct to standard infection control
precautions. It is therefore stressed that the nine elements of standard infection control precautions
must underpin all health and social care activities. It is therefore assumed for the purpose of this
literature review that all standard infection control precautions are being adhered to and therefore do
not require specifically addressed within this literature review and associated recommendations.
More information on the standard infection control precautions including associated literature reviews
is available from the Model Infection Control Policies website:
http://www.hps.scot.nhs.uk/haiic/ic/modelinfectioncontrolpolicies.aspx
5.1
General Principles of Transmission Based Precautions
5.1.1
Transmission Based Precautions are a set of precautions which can be implemented when
patients are either suspected or known to be infected with potentially transmissible infectious
agents.
5.1.2
The precautions are defined and grouped according to route of transmission of the particular
causative infectious agent.
5.1.3
A judgment on which transmission based precautions are required is based on clinical
symptoms or information on known outbreaks and precautions applied can be altered when
more specific information is received e.g. identification of causative agent by laboratory tests.
5.1.4
Transmission Based Precautions should be implemented based on clinical knowledge, while
awaiting actual identification of the causative agent and should be continued either for the
duration of illness or while still a risk of transmission.
5.1.5
The duration that transmission based precautions should be continued depends on a number of
factors such as the patient group affected.
5.2
Droplet Transmission
5.2.1
Droplet transmission is defined as the transfer of droplets from an infected respiratory tract
directly to a mucosal surface of another individual over a short distance.
5.2.2
Droplets from an infected respiratory tracts can be generated by normal human activities such
as coughing, sneezing, talking and breathing.
5.2.3
Infections that can be transmitted via this route include the influenza virus, rhinovirus,
adenovirus, Group A streptococcus and SARS- CoV.
5.2.4
Healthcare procedures such as intubation, nasopharyngeal aspiration, tracheostomy care, chest
physiotherapy, bronchoscopy and nebuliser therapy can cause aerosolisation of
microorganisms which usually transmit via droplets and therefore may require additional
precautions.
16
5.2.5
5.3
Medical conditions such as asthma, allergic rhinitis and chronic obstructive lung disease may
result in droplets from respiratory tract transmitting into the immediate environment, although
these may not be infectious, it may be advisable to take precautions.
Pathogens transmissible by droplets
5.3.1 Microorganisms which are transmissible by this route include Bordetella pertussis, influenza
virus, adenovirus, rhinovirus, Mycoplasma pneumoniae, SARS-associated coronavirus (SARSCoV), group A streptococcus, mumps, Parvovirus, rubella and Neisseria meningitidis.
5.3.2
There is some evidence that respiratory syncytial virus (RSV) is transmissible via droplets
although direct contact with the respiratory droplets is thought to be the most important route
of infection.
5.3.3
Scientific evidence indicates that some microorganisms not commonly transmitted by droplets
are occasionally disseminated in this way e.g. S. aureus has been shown to be disseminated via
the droplet route from the nose in both experimental and clinical situations, although this is
rare.
5.3.4
There have been new and emerging diseases which have been shown to transmit via droplets
e.g. SARS.
5.4
Epidemiologically important organisms
5.4.1
There is a growing list of microorganisms which are considered to epidemiologically
important, which can cause outbreaks within healthcare settings, and require additional
methods of infection prevention and control.
5.4.2
A number of these organisms are known to disseminate via the droplet route and include,
influenza, group A streptococcus etc.
5.4.3
The potential seriousness of HAI caused by any of these pathogens can be increased by the
setting , i.e. the occurrence of group A streptococcus within a Burns unit, or because of the
patient population affected and comparative severity of illness.
5.5
Potential Agents of Bioterrorism
5.5.1
There is additional information on a range of microorganisms which are potentially associated
with acts of bioterrorism.
5.5.2
Review of the scientific literature shows that a number of these organisms are believed to be
transmissible via the droplet route and therefore requiring droplet precautions as part of the
control strategy.
5.5.3
These organisms include Pneumonic Plague and there is some experimental evidence to show
that some viral haemorrhagic fevers e.g. Ebola, may disseminate via droplets, therefore
infection control advice may involve implementation of droplet as well as contact precautions.
17
5.5.4
It is recommended that eye protection is worn in addition to normal droplet precautions to deal
with cases of viral haemorrhagic fevers.
5.5.5
In the case of an outbreak caused by deliberate release, the advice given is that airborne
precautions should be used due to the lack of available knowledge about the causative strain.
Droplet Precautions
These are a set of precautions designed to prevent cross transmission of infectious agents, which are
transmissible by respiratory droplets and include the components below.
5.6
Spatial Separation
5.6.1
A 3 foot area around the patient has been considered as the potential zone of spread and the use
of this has been effective in the management of outbreaks of respiratory diseases.
5.6.2
However, recent studies particularly resulting from the SARS outbreak have suggested that
droplets could potentially spread as far as 6 feet from the source.
5.6.3
Therefore the recommendation of a precautionary distance of 3 feet should not be the single
deciding factor for implementation of droplet precautions such as donning of a mask.
5.6.4
A practical view may need adopted when deciding to implement droplet precautions e.g
donning a mask and it may be prudent to take precautions on entering the patient’s room,
particularly when dealing with newly emerging diseases of unknown etiology.
5.7
Respiratory Hygiene/Cough Etiquette
5.7.1
Review of studies on the SARS outbreak showed the importance of swift implementation of
infection control precautions as transmission to patients and staff often occurred at the triage
stage or point of entry to healthcare.
5.7.2
A strategy to deal with this has been recommended which is the introduction of respiratory
hygiene / cough etiquette as part of standard infection control precautions and transmission
based precautions.
5.7.3
Respiratory hygiene / cough etiquette is aimed at patients with undiagnosed respiratory
illnesses (coughing, sneezing etc) and is a fundamental component of droplet precautions.
5.7.4
Review of scientific literature shows that application of this precaution reduces the
transmission of respiratory infections via droplets.
5.7.5
Education and training of healthcare workers, patients and visitors specifically on rationale and
technique of respiratory hygiene / cough etiquette is required to promote compliance.
5.7.6
This can be achieved by the use of posters, leaflets and signs describing these precautions.
5.7.7
Respiratory hygiene/cough etiquette consists of covering the mouth and nose with disposable
tissue when coughing or sneezing followed by prompt disposal in suitable waste receptacle;
use of surgical masks by patient if possible; hand hygiene following contact with respiratory
18
secretions; separation of at least 3 feet between patients suffering from respiratory infections
within communal areas such as waiting rooms.
5.7.8
5.8
The wearing of masks by certain patient groups may not be practical within healthcare settings
such as paediatrics.
Hand Hygiene
5.8.1
Many studies specifically on hand hygiene have been reviewed and critically appraised within
the CDC guidance.
5.8.2
Hand hygiene is vital to prevent transmission of respiratory infections via droplets within the
healthcare environment.
5.8.3
All aspects of scientific literature on hand hygiene, including technique, when, where, how and
why has been extensively reviewed within the HPS model policy and associated literature
reviews.
5.8.4
The HPS hand hygiene model policy should be referred to for all aspects of hand hygiene
required for standard infection control or transmission based precautions.
5.9
Personal Protective Equipment
5.9.1
A main component of droplet precautions to prevent transmission of potentially infectious
droplets to directly to the mucous membrane therefore the use of Personal Protective
Equipment (PPE) is integral.
5.9.2
The use of disposable gloves forms part of standard infection control precautions to protect
from exposure to potentially harmful microorganisms that may be present in patient’s blood or
body fluids such as respiratory secretions.
5.9.3
Therefore the use of gloves is recommended within droplet precautions to protect from contact
with potentially contaminated respiratory secretions and droplets.
5.9.4
Details on all aspects of the use of disposable gloves as PPE are included within HPS model
infection control policy on PPE and associated literature reviews.
5.9.5
The role of gowns has been reviewed within currently available literature and guidance and
their use forms part of standard infection control precautions for protection from exposure to
potentially infected blood and body fluids.
5.9.6
Use of a surgical face masks as PPE for the purpose of droplet precautions has been reviewed
within the CDC guidance and HPS model policy and associated literature reviews.
5.9.7
The use of surgical masks has been reviewed within current guidance documents because
exposed mucosal surfaces of the nose and mouth can provide an easy route of entry to the body
for pathogenic microorganisms.
5.9.8
It is therefore recommended that masks and eye protection are worn for all healthcare
procedures that potentially generate splashes of blood and body fluids.
19
5.9.9
It has been shown within the primary reference source that the wearing of surgical face masks
by healthcare workers protects them from exposure to potentially infective respiratory droplets,
however for the purpose of transmission based precautions, PPE including masks and eye
protection, if required, must be donned prior to entering he patient area or room.
5.9.10 Specific advice and instruction regarding safe donning and removal of PPE, including gowns
is included in an appendix in the policy.
5.10 Additional Precautions - aerosol generating procedures
5.10.1 Recent scientific indicate that certain procedures e.g. intubation, nasopharyngeal aspiration,
tracheostomy care, chest physiotherapy, bronchoscopy and nebuliser therapy etc, in patients
suffering from respiratory illnesses considered transmissible only via droplets, can result in
generation of aerosols and therefore additional precautions will be required.
5.10.2 The use of suitable fit tested FFP3 respirators may be required in addition to gowns, gloves and
eye protection.
5.11 Patient Placement
5.11.1 The use of a single room is preferable for care of patients with respiratory infections
transmissible by droplets.
5.11.2 Alternatives involving the use of cohorting are possible and involve clustering of groups of
patients suffering from the same disease and this has been reviewed within recent scientific
literature and current guidance.
5.11.3 This approach is particularly relevant for outbreaks i.e. seasonal or pandemic influenza.
5.11.4 In addition, there are a significant number of studies looking at evidence to support other
options such as the use of spatial distance between beds of at least 3 feet and physical barriers
such as bed curtains.
6
References
Banning, M. (2006) Respiratory infection. Respiratory syncytial virus: disease, development and
treatment, British Journal of Nursing, 15, 751-5.
Brankston, G., Gitterman, L., Hirji, Z., Lemieux, C. and Gardam, M. (2007) Transmission of influenza
A in human beings, The Lancet Infectious Diseases, 7, 257-65.
Christian, M. D., Loutfy, M., McDonald, L. C., Martinez, K. F., Ofner, M., Wong, T., Wallington, T.,
Gold, W. L., Mederski, B., Green, K., Low, D. E. and Team, S. I. (2004) Possible SARS coronavirus
transmission during cardiopulmonary resuscitation, Emerging Infectious Diseases, 10, 287-93.
Collignon, P. J. and Carnie, J. A. (2006) Infection control and pandemic influenza, Medical Journal of
Australia, 185, S54-7.
Department of Health (2006) Immunisation against infectious disease - "The Green Book", DH,
London.
20
Department of Health (2007a) Bird flu and pandemic influenza: What are the risks?, DH, London.
Department of Health (2007b) Pandemic flu draft framework and guidance, DH, London.
Department of Health and Chief Medical Officer (2003) Severe Acute Respiratory syndrome (letter gateway reference no. 1439), DH (CMO), London.
Garner, J. S. (1996) Guideline for isolation precautions in hospitals. The Hospital Infection Control
Practices Advisory Committee., Infection Control & Hospital Epidemiology., 17, 53-80.
Gerber, S. I., Erdman, D. D., Pur, S. L., Diaz, P. S., Segreti, J., Kajon, A. E., Belkengren, R. P. and
Jones, R. C. (2001) Outbreak of adenovirus genome type 7d2 infection in a pediatric chronic-care
facility and tertiary-care hospital, Clinical Infectious Diseases, 32, 694-700.
Health Protection Agency (2005) SARS - hospital infection control guidance, HPA, London.
Health Protection Agency (2006) Health Protection Agency - Pandemic Influenza Contingency Plan,
HPA, London.
Health Protection Scotland (2007) Model Standard Infection Control Policies, HPS, Glasgow.
Kimura, A., Matsubasa, T., Kinoshita, H., Kuriya, N., Yamashita, Y., Fujisawa, T., Terakura, H. and
Shinohara, M. (1999) Helicobacter pylori seropositivity in patients with severe neurologic impairment,
Brain & Development, 21, 113-7.
Ng, K. S., Kumarasinghe, G. and Inglis, T. J. (1999) Dissemination of respiratory secretions during
tracheal tube suctioning in an intensive care unit, Annals of the Academy of Medicine, Singapore, 28,
178-82.
Scottish Executive Health Department and Health Protection Scotland (2005) Pandemic Influenza Infection Control Guidelines for use in hospitals and primary care settings, SEHD and HPS, Scotland.
Siegel, J., Rhinehart, E., Jackson, M., Chiarello, L. and The Healthcare Infection Control Practices
Advisory Committee (2007) Guideline for Isolation Precautions: Preventing Transmission of
Infectious Agents in Healthcare Settings 2007, June 2007.
Scottish Intercollegiate Guidelines Network (2004) SIGN 50: A guideline developers' handbook,
SIGN, Edinburgh.
Tablan, O. C., Anderson, L. J., Besser, R., Bridges, C. and R., H. (2004) Guidelines for Preventing
Healthcare Associated Pneumonia, 2003, MMWR - Morbidity & Mortality Weekly Report Recommendations and Reports, 53, 1-36.
Tellier, R. (2006) Review of aerosol transmission of influenza A virus, Emerging Infectious Diseases,
12, 1657-62.
The AGREE Collaboration (2001) Appraisal of Guidelines For Research & Evaluation (AGREE)
Instrument, September 2001.
Wang, W. K., Chen, S. Y., Liu, I. J., Chen, Y. C., Chen, H. L., Yang, C. F., Chen, P. J., Yeh, S. H.,
Kao, C. L., Huang, L. M., Hsueh, P. R., Wang, J. T., Sheng, W. H., Fang, C. T., Hung, C. C., Hsieh, S.
M., Su, C. P., Chiang, W. C., Yang, J. Y., Lin, J. H., Hsieh, S. C., Hu, H. P., Chiang, Y. P., Yang, P.
21
C., Chang, S. C. and Hospital, S. R. G. o. t. N. T. U. N. T. U. (2004) Detection of SARS-associated
coronavirus in throat wash and saliva in early diagnosis, Emerging Infectious Diseases, 10, 1213-9.
World Health Organisation (2004) Practical Guidelines for Infection Control in Healthcare Facilities,
WHO, Geneva.
World Health Organisation (2006a) Avian Influenza, including Influenza A (H5N1), in humans: WHO
Interim Infection Control Guideline for Health Care Facilities, WHO, Geneva.
World Health Organisation (2006b) Infection Control Recommendations for Avian Influenza in
Healthcare Facilities, WHO, Geneva.
World Health Organisation and International Federation of Red Cross and Red Crescent Societies
(2001) Infections and Infectious Diseases - A manual for nurses and midwives in the WHO European
Region, WHO and IFRC & RCS, Geneva.
Zamora, J. E., Murdoch, J., Simchison, B. and Day, A. G. (2006) Contamination: a comparison of 2
personal protective systems., CMAJ Canadian Medical Association Journal., 175, 249-54.
22