Cryptosporidiosis outbreak Carlow Town - 2005

1. Cryptosporidiosis outbreakCarlow Town - 2005 Mr John Carley, Senior Engineer, Water Services, Carlow County Council. Carlow Co. Co. are the sanitary authority for County Carlow, responsible for the production of drinking water to the requirements of the European Communities (Drinking Water) Regulations, SI 439 0f 2000. Role of Senior Engineer in Managing the incident • Responsible for the management of the outbreak for Carlow Co. Co., reporting to the Director of Services for Infrastructure, Water Services & Environment. This included : • Investigation of the water supply to Carlow Town incl. monitoring of the Water Supply for presence of cryptosporidium. • Implementation of process control improvements at Sion Cross WTW. • Fast tracking of construction of booster station to augment water supply to Carlow Town from Rathvilly WTW. • Public Relations. • Member of the Carlow Co. Co. Incident Response Team and the joint CCC / HSE-SE Incident Response Team.

2. Cryptosporidiosis outbreakCarlow Town - 2005 Crytposporidium in Water Supplies • Surface and ground waters abstracted for drinking water become contaminated as a result of : • Run off from agricultural land on which infected animals have defecated • Run off from agricultural land following the spreading of slurry • Discharge from sewage treatment works or septic tanks • Rodent or bird droppings in surface water • Outbreaks particularly occur during lambing/calving season March/April and in the Autumn period, Sept/Oct. • Oocysts are resistant to disinfection treatment using chlorination. • Coagulation, flocculation and filtration can be effective in removing majority of oocysts.

3. Cryptosporidiosis outbreakCarlow Town - 2005 Legislation • Circular L7/98 from DEHLG “Protection of Water Supplies from Contamination by Cryptosporidium” • EC (Drinking Water) Regulations, 2000 (SI 439 of 2000) • Test for Clostridium Perfringens and if present, test for Cryptosporidium. • Water Supply (Water Quality) Regulations 2000 – England and Wales and Cryptosporidium (Scottish Water) Directions 2003 • Must monitor for presence of Cryptosporidium and no. of oocysts must be less than 1 per 10 litres • Unofficial trigger level for investigation in Scotland and Northern Ireland of 0.1 litres per 10 litres

4. Cryptosporidiosis outbreakCarlow Town - 2005 Carlow Town Water Supply • Rathvilly • River Slaney • Conventional Surface Water Treatment Plant – commissioned in 1987. • Average water production 6,960 m3 per day – nominal design capacity 9,600 m3 • Supplies 4,000 m3 per day to carlow Town • Sion Cross • River Burren • Conventional Surface Water Treatment Plant – two treatment streams • Treatment stream no. 1 – horizontal flow sedimentation tank – 1950’s • Treatment stream no. 2 – hopper bottom sedimentation tanks – 1970’s • Supplies 4,000 m3 per day to Carlow Town, with a design capacity in excess of 4,000 m3 per day.

7. Cryptosporidiosis outbreakCarlow Town - 2005 Chronology of Event – pre boil water notice 2nd March 2005 – advised by HSE-SE of 3 confirmed cases of cryptosporidiosis in Carlow Town 8th March 2005 – 0.04 oocysts per 10 litres confirmed in one of two samples taken. - Immediate flushing of Carlow Town Water Supply carried out. - Follow up testing was negative for cryptosporidium - Testing of final water at Sion Cross & Rathvilly negative for cryptosporidium 14th March 2005 – first meeting of Carlow Co Co / HSE SE Incident Response Team. - results of water sampling did not warrant issuing of boil water notice at this stage Agreed - • Carlow Co Co to continue monitoring for cryptosporidium. • HSE SE to continue enhanced surveillance for cryptosporidium. • Incident Response Team to meet on an ongoing basis

8. Cryptosporidiosis outbreakCarlow Town - 2005 Actions by Carlow Co Co – Pre Boil Water Notice • Ongoing monitoring for cryptosporidium carried out on distribution network and at treatment plants. • Daily monitoring of Sion Cross WTW for turbidity and clostridium perfringens. • Procurement of planned pumping station to boost water supply from Rathvilly to Carlow Town expedited. • Quantity of water produced at Sion Cross was temporarily reduced but this was found to be unsustainable due to water demand. • Second cryptosporidium laboratory (Dublin City Council) employed.

9. Cryptosporidiosis outbreakCarlow Town - 2005 Chronology of Event – issuing of boil water notice • Boil Water Notice issued 14th April by Carlow Co Co on the advice of the HSE SE. • Boil Water Notice was issued by way of leaflet drop to all affected properties and was advertised on local radio and in local newspapers.

10. Cryptosporidiosis outbreakCarlow Town - 2005 Action by Carlow Co Co during the Boil Water Notice • Sion Cross was determined to be a Very High Risk Supply for cryptosporidium. Works were based on : • Reducing quantity of water produced at Sion Cross • Placing Greater Control on the water produced at Sion Cross • Friarstown Booster Station – additional 2,000 m3 from Rathvilly to Carlow Town. • Sion Cross Treatment Plant • Older treatment stream decommissioned (Horizontal flow settlement tanks) • Improvement works including : • Turbidity monitors on each sand filter outlet • Filters run to waste for a period following backwashing • Uprating of coagulant plant • Uprating of polyelectrolyte plant

11. Cryptosporidiosis outbreakCarlow Town - 2005 • Water Conservation • Inspection of Burren River catchment • Animal carcasses found in the river

12. Cryptosporidiosis outbreakCarlow Town - 2005 Chronology of Event – Lifting of boil water notice Criteria for lifting of Boil Water Notice agreed by Carlow Co Co / HSE SE • 24 hr sampling of cryptosporidium to be carried out at Sion Cross, Rathvilly and on the distribution network, with an acceptable level of oocysts agreed at 0.05 oocysts per 10 litres – samples to be acceptable for 7 consecutive days. • Epidemiological evidence that outbreak was over – ie no new cases • Daily sampling for cryptosporidium to continue for a month following lifting of notice • Monthly monitoring of river catchments to be carried out • Local Liaison Group to continue to meet • HSE SE to continue enhanced surveillance of human cryptosporidiosis • The Boil Water Notice was lifted by Carlow Co Co on 24th May 2005, on the advice of the HSE SE, when all of the agreed criteria had been satisfied.

13. Cryptosporidiosis outbreakCarlow Town - 2005 Sampling • Cryptosporidium • Filters • Filta Max, manufactured by IDEXX • Envirocheck, manufactured by PALL Corporation. • Laboratories • City Analysts, Ringsend, Dublin • Dublin City Council • Scottish Water, Edinburgh, Scotland • Turbidity • EC (Drinking Water) Regulations 2000 specify a parametric value not exceeding 1.0 NTU (1988 Drinking Water Regulations specified a max. value of 4.0 NTU) • Should be used as a real time indicator of the treatment plant performance

14. Cryptosporidiosis outbreakCarlow Town - 2005 Crytposporidium Species • Many different types, not all capable of infecting human hosts • Species identification of oocysts detected in water samples was undertaken by Scottish Parasite Diagnostic Laboratory. • C. Andersoni identified on 4 of 6 slides. • C. Andersoni / C. Muris identified on 2 slides • C. Parvum identified on 1 slide. • C. Andersoni, is of Cattle origin, and is not recognised as being pathogenic to humans

15. Cryptosporidiosis outbreakCarlow Town - 2005 Risk Assessments • Sion Cross score pre improvement works = 117

16. Cryptosporidiosis outbreakCarlow Town - 2005 Communication • Inform local councillors of Boil Water Notice. • Interviews given on local radio in advance of issuing notices to households. • Interviews given to National newspapers, television and radio. • Hard copy of notice hand delivered to all affected properties. • HSE SE and CCC staff attended Council meetings to answer queries • Information notice to Hotels, Bars and restaurants. • Advertisements on local radio. • Freephone helpline, 24 hours each day, 7 days of week. • All info provided on Carlow Co Co website • Regular information updates provided on local radio. • Information updates delivered to all affected properties (12,000 approx.) • Lifting of notice communicated through leaflet drop and on local radio / newspapers.

17. Cryptosporidiosis outbreakCarlow Town - 2005 Lessons Learned • Routine monitoring of water supplies for cryptosporidium required. • Regional public laboratories required for testing for cryptosporidium. • Risk assessments required on all surface water supplies. • Turbidity to be used as a realtime indicator of water treatment performance • In line turbidity monitors are required, with the monitors alarmed. • Turbidity levels to be used to control the process of backwashing sand filters and the return to services of sand filters. • Use of particle counters should be considered. • Training required for water treatment plant operators in Cryptosporidium awareness. • Location of sewer and septic tank outfalls in river catchments used for drinking water abstraction should be recorded and mapped.