Risk to public health associated with private water supplies Dr Emmanuel Okpo Private Water Supply Workshop October 2013
Outline • Water quality standards/drivers • Contaminants (pathogens, chemicals) • Population at Risk • Health Risk • An example- E coli O157 outbreak in Grampian
Private water Quality Standards The Private Water Supply (Scotland) regulations 2006 Drinking Water Directive 98/83/EC ‘…. to protect human health from the adverse effect of any contamination of water intended for human consumption by ensuring that it is wholesome and clean’
Other Quality drivers • The Water Quality (Scotland) Regulations 2010 • WHO Guidelines on Drinking Water Quality – 4th edition • E coli O157 Task Force Report 2001 • To provide clean and wholesome water to rural communities in Scotland
Contaminants • Quality of private supplies variable depending on the source • Main contaminants: – micro-organisms i.e. bacteria, protozoa, parasites and viruses (s) and – Chemicals- Lead, Nitrates, Iron, Arsenic, manganese – Pesticides & by products
Sources of contamination • Direct or indirect faecal contamination • Domestic and farm animals-defecating in or near watercourses • Wildlife and humans • Run off from agricultural land after slurry spreading or grazing • Leakage of stored manure/pesticides • Leakage or poorly functioning septic tanks • Environment
Population affected • Over 150,000 in Scotland • Lots more on holiday – campsites, Bed and Breakfast, holiday lets • In 2012, 19,916 registered PWS (2,434-type A & 17,482 -Type B)- 39% in Aberdeenshire -7,676 registered PWS • 32,000 people in Grampian • Mostly in Aberdeenshire (13% of popln on PWS)
Risk to public health • Contaminated water can cause severe illness & outbreak of diseases • Illness -immediate/long term • 10 x more likely to become ill (HPS) • Children under 4X likely to suffer diarrhoea than others
Health Risks Pathogens Definition & Health effect • Some E coli harmless or cause mild disease E Coli O157 • Verocytotoxic E coli – severe disease • Diarrhoea, bloody diarrhoea, abdominal pain • HUS, acute renal failure and death • Very low infective dose • Incubation period 2-5 days (1-14 days) • Also O111, O26, O103, O145 – Europe • Single-celled protozoan parasite- C. parvum and C. hominis Cryptosporidium • found in lakes and rivers -contaminated with sewage and animal waste. • Low infective dose – 10 oocysts- (Calves/ lambs-oocysts 10 9 oocysts/day) resistant to chlorine, can survive for months- Bacteria not good indicator • Acute, self limiting GI illness up to 4 weeks • Severe in immuno-compromised patients- Can be fatal • Incubation period 7-10 days (1-28 days) • Need physical barrier-filtration, coagulation, sedimentation
Health Risks Pathogens Definition & Health effect • Commonest cause bacterial gastro-enteritis Campylobacter • Low infective dose • Diarrhoea, abdominal pain and vomiting • Short lived illness but can be serious • Reactive arthritis, Guillain-Barre and HUS • Incubation period 2-5 days (1-10 days) • Giardia Lamblia lives in the intestine of infected humans or animals • found on surfaces or in soil, food, or water that has been contaminated with the faeces from infected humans or animals • Cyst resistant to chlorine • Need physical barrier e.g. filtration, sedimentation • Low infectivity dose- GI illness • Viruses (enteric) Intestine of infected humans or animals • Polioviruses x3, coxsackieviruses, echoviruses, and other enteroviruses, Coxsackie A viruses, Coxsackie B viruses, echoviruses, • Gastroenteritis -rotavirus and norovirus • meningitis – echovirus, myocarditis -Coxsackie B.
Health Risks Chemicals Definition & Health effect • Lead Toxic metal, household plumbing-pipes, solder, fixtures and faucets (brass), and fittings- Soft water dissolves lead from pip • Infants and children- delays in physical or mental development • deficits in attention span and learning abilities. • Adults – long term mainly kidney problems or high blood pressure Nitrate • Septic tank, animal manure, fertilizers, pesticides, erosion of natural deposits • Babies & infants- Blue-baby syndrome • Arsenic Erosion of natural deposit, runoff from industrial waste (glass/electronic) • skin damage, problems with their circulatory system, increased risk of cancer.
Waterborne outbreaks • Scotland 1945 – 1987 (Benton et al 1989) – 57 waterborne outbreaks – 21 (37%) private supplies affecting 9362 people (Lamb et al 1998) More recently ………
Outbreaks of Infectious Intestinal Disease (Main mode of transmission- ‘waterborne’) 2008-2012 . Year Organism Location Total ill Total ill Source and positive 2008 E.coli O157 Private houses 15 12 PWS 2008 E.coli O157 & Farm 3 2 PWS Non O157 E.coli 2010 E.coli O157 Holiday 15 10 PWS accommodation 2012 Campylobacter & Hospital 27 3 PWS Cryptosporidium Source: ObSurv - Health Protection Scotland 2013
Locking M. et al 2010. Private water supplies in Scotland- Still an important source of E Coli O157 outbreak?
An Outbreak of E.coli O157 infection in Aberdeenshire
The Setting
Friday 22 August • Case 1 notified and interviewed • Private water supply • Initially 10 households • Eventually dropped to 8 households • Aberdeenshire over 7500 supplies, serves more than 11000 properties • 3 Others on PWS with similar illness identified and interviewed
Monday 25 August • All households on PWS interviewed except 1 • 2 further positive cases notified by ARI Labs • Outbreak declared • OCT convened
Epidemiology 7 6 No. in age group 5 • 30 residents in 8 properties 4 3 – 16 male, 14 female 2 1 0 – 11 = age <16 0-4 5-9 10- 15- 20- 25- 30- 35- 40- 45- 50- 55- 60- 14 19 24 29 34 39 44 49 54 59 64 3 – 15 symptomatic 2 – 6 male (15 – 60) 1 – 9 female (5 – 42) 0 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 . . . . . . . . . . . . . . . . . . 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 – 5 = age <16 . . . . . . . . . . . . . . . . . . 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 1 1 1 1 1 1 1 1 1 1 2 2 2 2 2 2
Epidemiological investigation 15 asymptomatic 15 symptomatic 12 symptomatic 3 asymptomatic E.Coli O157 +ve E.Coli O157 +ve 15 asymptomatic 15 cases E.coli O157 15 symptomatic 12 asymptomatic 3 symptomatic E.Coli O157 -ve E.Coli O157 -ve All isolates E.coli O157 phage type 32 - indistinguishable
Control measures • Boil notice issued on 22 August • Case finding – 9 households interviewed • Human sampling – started 22 August • Infection control advice – hand washing and environmental hygiene • Exclusion in accordance with NHS Grampian Exclusion Policy – total of 9 individuals excluded
Water Supply Borehole – Good condition, well sealed & housed, pumps submerged – 30 metres deep Storage tank – stainless steel, good condition – Mud & stagnant water around base – No fencing around tank – Cattle nearby Pipeline – Wet areas but no leaks identified
Environmental Investigation Borehole Houses Animal trough Animal trough
Environmental Investigation Animal trough - adjacent 2 Storage tank Borehole 1 4 Animal trough – new 3 1. One way valve not working - ? Backflow into borehole 2. Valve controlling water supply not ? Back flow functioning into supply 3. Similar valve to no 2 4. No treatment before houses
Results Environmental results – Kitchen tap - E.coli O157 phage type 32 – Storage tank – E.coli O157 phage type 32 – Animal trough 2 – E.coli O157 phage type 32 – Animal trough 1 - E.coli O157 phage type 14 – Borehole and samples around storage tank negative. – Borehole negative X3 then positive suggesting ongoing faecal contamination from cattle in field PFGE – human and animal E.coli O157 phage type 32 cultures indistinguishable
Improvements • Storage tank & borehole fenced off • Cattle troughs supplied from storage tank • Faulty valves at troughs replaced • Chlorinated X 2 • 8 point of entry ultraviolet filters for houses • ‘Relevant person’ given advice
Conclusion • Outbreak of E.coli O157 infection epidemiologically, environmentally and microbiologically linked to contaminated private water supply • Limited severity of disease but high attack rate seen • Potentially preventable with risk assessment and treatment on supply • Highlights the need for treatment on these water supplies • Need to raise awareness of advice and financial assistance
Thank you for listening
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