Waterborne outbreak investigation in Finland

1. Waterborne outbreak investigation in Finland Dr. Outi Zacheus National Public Health Institute (KTL) Kuopio, Finland

2. Ground water 58% of the production the use of ground water is increasing small production units alkalization is often the only treatment rarely disinfected Surface water around 70 waterworks mainly in large cities large production units multistage purification processes disinfection mainly with chlorine Production of drinking water

3. Reporting of waterborne outbreaks since 1997 • Systematic and rapid information of all possible waterborne outbreaks with a standardized questionnaire • immediate reporting before confirmation analysis of an outbreak • by fax to National Public Health Institute • to accelerate the co-operation • to improve the design of immediate actions

4. Reporting questionnaire • Estimated date and place of an outbreak • Number of exposed and sick persons • Symptoms • Suspected causative agent • Samples taken (drinking water, raw water, patients) and analyses intended to carry out • Contact person

5. Flow of information:food poisoning and waterborne outbreaks Health Inspection - responsible authority National Public Health Institute - expertise National Food Agency Ministry of Social Affairs and Health National Veterinary and Food Research Institute Ministry of Agricultural and Forestry Healthcare Region County Reporting questionnaire Information in special cases

6. Waterborne outbreaks since 1997 • Waterborne outbreaks have been caused by small public waterworks and private wells (camping sites, resort willages). • Most outbreaks have been associated with the use of ground water. • Reasons to the outbreaks: flooding (raining, melting of snow), surface run-off, leakage in pipeline, insufficient treatment

7. Causative agents • Waterborne outbreaks have been caused by caliciviruses and campylobacteria. • Improved PCR methodology enables the detection of viruses and bacteria both from patients and from drinking water.

8. Recognition of outbreaks • Sudden increase of illness cases • Bad smell and taste of water • Routine water quality monitoring • usually does not indicate an waterborne outbreak, but reveals basic water quality • Positive results of indicator organisms • Positive results of pathogenic agents

9. Immediate actions • Termination of the use of contaminated drinking water • use of alternative sources of drinking water • Immediate instructions to consumers • boiling instructions of drinking water • Start of chlorination (shock chlorination, supplementary chlorination) • Sampling

10. Sampling • Immediate collection and storage of water samples • drinking water and raw water samples • high amount of samples • large volume of samples • routine microbiological and physical-chemical analysis and pathogenic agents • Analysis of stool samples from sick persons

11. Problems with outbreak detection • Common unbelief in the outbreak • Low number of illness cases • sick persons do not consult a doctor • Negative results of indicator organisms and causative agent • delayed sampling, passing contamination • low volume of samples, high detection limit

12. Epidemiological study • Extent of an outbreak • number of illness cases • number of persons being exposed • Duration of an outbreak • Source of an outbreak • Useful tool if results of indicator organisms and causative agent are negative

13. Advantages of the reporting system • The detection limit of waterborne outbreaks has decreased. • more realistic statistics on outbreaks • Awareness of problems associated with drinking water has increased. • Co-operation between authorities, health care, waterworks, laboratories and KTL has improved.