Download A Public Health Issue

Water Services National Training Group
and
National Federation of Group Water
Schemes
7th Annual Rural Water Services
Conference
18th September 2008
Safety & Security of Water Supplies
- A Public Health Issue
Dr. Heidi Pelly,
Consultant, Public Health Medicine,
Health Services Executive
Terminology
• A pathogen is a microorganism capable of
causing disease in a host
• Waterborne pathogens excreted in faeces
of humans/animals, transmitted via
ingestion
• Water-based pathogens occur naturally in
water, usually not transmitted person to
person (e.g. Legionella spp.)
Importance of Waterborne
Pathogens
• Increased sensitive subpopulations
• Recognition of important additional health
effects, including chronic sequelae
• Natural evolution of microbes with
increased virulence
• Development of molecular techniques
leading to improvements in detection of
outbreaks and their sources.
Agents of Waterborne or Water-based
Disease
• Bacteria:
Shigella spp.
Toxigenic E. coli
Campylobacter spp
• Viruses:
Norovirus
Rotavius
Hepatitis A
• Protozoa:
Cryptosporidium spp
Giardia
Toxoplasma Gondi
•Waterborne outbreaks generally caused
by failed/absent treatment processes
•Greatest infectivity, small dose cause
infection, longer environmental survival.
Removal by filtration inefficient, more
resistant to disinfection.
•Single cell organism, thick wall highly
resistant to disinfection
Landmark Water Incidents
• International
– Soho 1854 – Cholera
outbreak ( John Snow)
– Hamburg 1892 –
Cholera epidemic
– Swinden 1989 –
Cryptosporidium
– Milwaukee 1993 –
Cryptosporidium
– Walkerton – E. coli
•National
- Naas 1992
- Nenagh 1996
- Mullingar 2002
- Galway 2007
Current Situation
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944 Public water supplies
777 Public group water schemes (GWS)
706 Private GWS
100,000 – 200,000 Private wells
• 85% surface water
• Increasing demand
Legislation
Water Services Act 2007
• ‘protection of human health’
• ‘protection of public health’
• ‘public authority’ includes Health Service
Executive
• ‘water services authority’ replaces ‘sanitary
authority’
Drinking Water Regulations
S.I. No. 278 of 2007
Protection of human health
– Para 9 (1) Where a sanitary authority, in consultation with the
HSE, considers that a supply of water intended for human
consumption constitutes a potential danger to human health, the
authority shall, subject to agreement with the HSE, ensure that
…..
– Para 9 (2) …. Subject to agreement with the HSE … the
supervisory authority shall issue such direction to the relevant
water supplier as it considers necessary….
Drinking Water Regulations
S.I. No. 278 of 2007
Departures from standards
– Para 11 (1) A departure from the parametric
values…. may …. subject to the agreement of
the HSE, be granted by the Agency……
Confirmed in writing by the Medical Officer of
Health (EPA Handbook)
Infectious Disease Regulations
S.I. No. 390 of 1981
• Para 11 On becoming aware … of a case or a
suspected case of an infectious disease or of a
probable source of infection with such disease, a
medical officer of health… shall make such
enquiries and take such steps as are necessary
… for investigating the nature and source of
infection, for preventing the spread of such
infection and for removing conditions favourable
to such infection
Other Relevant Legislation
• Food safety
– Food Hygiene Regulation S.I. No. 205 of 1950
– EC Regulation No 852/2004
• hygiene of foodstuffs
• requires the use of potable water in connection
with the food business
• S.I. No. 369 of 2006 gives effect in Irish law
• Fluoridation Regulations S.I. No. 42 of 2007
Current Procedures
• Routine
- Water Liaison Group
•Incidence Response
Team
-Water monitoring results
- Protocols/guidelines
-Acute infections
- Water monitoring
programme
- Surveillance of
notifiable disease
-Increase/outbreak of
human illness
Environmental Health Service
• First point of contact with HSE
• Water monitoring programme for local
authorities
• Water monitoring under food safety
legislation
• Fluoridation (Dentists)
• Environmental expertise
Laboratory Services
• Clinical Laboratories
- Patient specimens
• Public Health Laboratories
- Water & environmental specimens
• Public Analyst Laboratories
• Reference Laboratories
• Consultant microbiologist
Public Health Department
• Surveillance of notifiable infectious disease
- Receive notifications
- Enhanced surveillance
- case finding
- HPSC
• Investigation
- Epidemiological studies – descriptive/analytical
- International evidence
- Expert advice
• Staff
- Public Health Doctors – MOH
- Surveillance Scientists
- Communicable Disease Nurse
Public Health Advice
• Health and other professionals
• Vulnerable groups
- Immunocompromised
- Infants
- Elderly
• General public
• Risk Communication
Health Protection Surveillance Centre
• Collate date on notifiable infections at
national level
• Support preparation of national
guidelines/advice/IT systems e.g. CIDR
• Monitors trends
• Annual reports. e.g.
Annual report of HPSC 2002
•7/64 outbreaks associated with suspect waterborne or waterborne combined
with other route of transmission
•However, these outbreaks contributed to over 40% reported cases of
infectious intestinal disease
Protection Of Human Health
• Assessment of the risk
- Is there a problem
- what is the cause
• Identification of the population affected
- Vulnerable groups
- Vulnerable sites
• What can be done now
• What can be done to stop it happening
again
Boil Water Notice
• Advantages – immediate and effective
• Disadvantages
- Compliance
- Duration
- Criteria for lifting
- Resources
- Burns/scalds
- Alternative supplies
- Loss of confidence
Critical Review of Waterborne Disease
Outbreaks.
Hrudley and Hrudley 2007
Cryptosporidium,
Campylobacter,
Giardia,
Norovirus,
Pathogenic E. Coli,
Unidentified,
Rotavirus,
Shigella,
Hepatitis A
Salmonella
Toxoplasmosis
20
14
13
12
7
5
2
2
1
1
1
Factors contributing to these
outbreaks
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Wastewater contamination
Inadequate knowledge of source water hazards
Inadequate disinfection
Extreme weather (heavy rain & runoff)
Filtration failures
Cross-connections and distribution failures
Livestock/wildlife faecal contamination
Plant maintenance/treatment process changes
Factors contributing to outbreak
failures
• “More than one mechanism was involved in
contributing to each outbreak, and vulnerable
conditions had often been in place for years, if
not decades. In hindsight, all of these
outbreaks were preventable, often with even
a modest level of foresight and care.”
• “ The preventive measures required are all
things that we know how to do.”
Relying on Microbiological
Evidence of Disease
•
•
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Asymptomatic disease
An infected person may not visit doctor
The doctor may not seek a stool specimen
The patient may not provide a specimen
The appropriate test may not be requested
The test may be done incorrectly
The test may be unable to detect pathogens
present
• There may be delays in laboratory reporting.
The World’s Water Supply
If all earth’s water fit in a gallon
jug, available fresh water
would equal just over a
tablespoon – less than half of
one percent of the total. About
97 percent of the planet’s
water is seawater and another
2 percent is locked in icecaps
and glaciers. Vast reserves of
fresh water underlie earth’s
surface, but much of it is too
deep to economically tap.
References
• Hrudley, S. E; Hrudley, E. J. (2007)
Published Case Studies of Waterborne
Disease Outbreaks – Evidence Of a
Recurrent Threat. Critical Review. Water
Environment Research, 79 (3), 233 – 245.
Acknowledgments
• Dr. BethAnn Roch, HSE South (SE).
• Dr Tessa Greally, HSE West (MW)
Water Services National Training Group
and
National Federation of Group Water
Schemes
7th Annual Rural Water Services
Conference
18th September 2008