Cryptosporidium oocysts in a water supply associated with a cryptosporidiosis outbreak - PubMed (original) (raw)

Cryptosporidium oocysts in a water supply associated with a cryptosporidiosis outbreak

Andrew D Howe et al. Emerg Infect Dis. 2002 Jun.

Abstract

An outbreak of cryptosporidiosis occurred in and around Clitheroe, Lancashire, in northwest England, during March 2000. Fifty-eight cases of diarrhea with Cryptosporidium identified in stool specimens were reported. Cryptosporidium oocysts were identified in samples from the water treatment works as well as domestic taps. Descriptive epidemiology suggested that drinking unboiled tap water in a single water zone was the common factor linking cases. Environmental investigation suggested that contamination with animal feces was the likely source of the outbreak. This outbreak was unusual in that hydrodynamic modeling was used to give a good estimate of the peak oocyst count at the time of the contamination incident. The oocysts' persistence in the water distribution system after switching to another water source was also unusual. This persistence may have been due to oocysts being entrapped within biofilm. Despite the continued presence of oocysts, epidemiologic evidence suggested that no one became ill after the water source was changed.

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Figures

Figure 1

Figure 1

Date of diarrhea onset, 58 cryptosporidiosis cases, Clitheroe, 2000.

Figure 2

Figure 2

Mean daily cryptosporidia oocyst counts from 10-L grab samples taken during outbreak

References

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    1. Standing Committee of Analysts. Isolation and identification of Cryptosporidium oocysts and Giardia cysts in waters 1999. Methods for the examination of waters and associated materials. Bristol, England: Environment Agency; 1999.

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