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Cryptosporidium oocysts in a water supply associated with a cryptosporidiosis outbreak.

Howe AD, Forster S, Morton S, Marshall R, Osborn KS, Wright P, Hunter PR - Emerging Infect. Dis. (2002)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: East Lancashire Health Authority, Nelson, United Kingdom.

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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Mean daily cryptosporidia oocyst counts from 10-L grab samples taken during outbreak
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Figure 2: Mean daily cryptosporidia oocyst counts from 10-L grab samples taken during outbreak

Mentions: On March 17, a large-volume sample of water (1,627 L) from a pumping station fed from Lowcocks WTW yielded 76 oocysts of Cryptosporidium per 1,000 L. Cryptosporidium oocysts were also identified in a water sample taken from a domestic tap in the water zone on March 16 at a concentration of five oocysts per 10 L of water. From March 16 to April 6, a total of 192 samples (10-L grab samples) from domestic taps or fire hydrants in the affected zone were analyzed; 47 (24%) contained Cryptosporidium oocysts in concentrations ranging from 1 to 9/10 L. Six water samples from domestic taps in areas adjoining the affected water zone were negative (Table 2, Figure 2).


Cryptosporidium oocysts in a water supply associated with a cryptosporidiosis outbreak.

Howe AD, Forster S, Morton S, Marshall R, Osborn KS, Wright P, Hunter PR - Emerging Infect. Dis. (2002)

Mean daily cryptosporidia oocyst counts from 10-L grab samples taken during outbreak
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3369585&req=5

Figure 2: Mean daily cryptosporidia oocyst counts from 10-L grab samples taken during outbreak
Mentions: On March 17, a large-volume sample of water (1,627 L) from a pumping station fed from Lowcocks WTW yielded 76 oocysts of Cryptosporidium per 1,000 L. Cryptosporidium oocysts were also identified in a water sample taken from a domestic tap in the water zone on March 16 at a concentration of five oocysts per 10 L of water. From March 16 to April 6, a total of 192 samples (10-L grab samples) from domestic taps or fire hydrants in the affected zone were analyzed; 47 (24%) contained Cryptosporidium oocysts in concentrations ranging from 1 to 9/10 L. Six water samples from domestic taps in areas adjoining the affected water zone were negative (Table 2, Figure 2).

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: East Lancashire Health Authority, Nelson, United Kingdom.

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.

Show MeSH
Related in: MedlinePlus