Cryptosporidium and Giardia are two waterborne protozoan pathogens affecting humans and animals and causing diarrheal diseases throughout the world. Water is the main transmission route of the disease and both enteric parasites are released in the environment through the faeces of infected hosts. The ubiquitous occurrence of Cryptosporidium and Giardia in drinking water reservoirs represents a potential threat to the drinking water production. Monitoring schemes have consequently been implemented in many countries. In such monitoring frameworks, sampling strategy is of key importance because it affects the representativeness of the underlying microbial risk. However, appropriate sampling designs require sound knowledge of the spatial dynamics of both parasites in the watershed.
The present study has therefore examined the spatial and temporal scales of Cryptosporidium and Giardia distribution dynamics in the Upper-Sûre watershed and in the reservoir of Esch-sur-Sûre, the latter acting as drinking water supply for 80% of the Luxembourg population. Results have important implications for the monitoring of the microbial risk associated to Cryptosporidium and Giardia occurrence in drinking water resources. Recommendations are provided for the establishment of monitoring schemes aim at assessing the underlying public health risk.
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