CRYPTOSPORIDIUM IN DRINKING WATER - SURVEY OF OCCURRENCE

Report No FR0207

D G Miller and E G Carrington

June 1991

SUMMARY

I OBJECTIVE

To assess the degree of occurrence, seasonal patterns and origins of cryptosporidium oocysts in a selected number of river and groundwater sources.

II REASONS

Outbreaks of cryptosporidiosis have been related to water supplies. The Badenoch Committee recommended that information should be obtained on the degree of occurrence in water sources and that effort should be concentrated on an intensive survey of a few selected sources.

III CONCLUSIONS

The report summarises the results obtained from the national survey involving three river stretches and six boreholes for the final period of study. Again the levels of oocysts measured in the river sources have been low and have not triggered the second stage programme to identify sources. The borehole sources have all given negative results for this period. This means that for the whole 12 month period oocysts have been much below the levels recorded in other sources such as those surveyed in the United States. Even allowing for the likely under recovery of oocysts inherent in the analytical method it is unlikely that sufficient oocysts have been present to represent a threat to health and this has been borne out by the parallel epidemiological studies carried out by CDSC with funding from DoE. The results will now be fully analysed and included in a full final report on the survey to be prepared in the next quarter.

Arrangements for the survey of Loch Lomond have been finalised and the study has commenced with joint funding from FWR and the Central Scotland Water Development Board. Quality assurance is being funded by the Department of the Environment.

Copies of the report are available from FWR, price 15.00, less 20% to FWR Members.