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Cryptosporidium during a simulated outbreak
Author(s) -
Gale Paul,
Stanfield Geoff
Publication year - 2000
Publication title -
journal ‐ american water works association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.466
H-Index - 74
eISSN - 1551-8833
pISSN - 0003-150X
DOI - 10.1002/j.1551-8833.2000.tb09009.x
Subject(s) - cryptosporidium , outbreak , veterinary medicine , environmental science , environmental health , biology , medicine , feces , virology , microbiology and biotechnology
Monitoring programs often underestimate the total oocyst loading and, thus, the risk of infection. Counts of Cryptosporidium oocysts in 100‐L volume “spot” samples of treated water have been simulated for conditions representative of an outbreak. The counts agree well with those reported in outbreaks in the United Kingdom and the United States. Whereas 33 percent of 100‐L samples contained no oocysts, a small proportion contained hundreds and even thousands of oocysts. The risk of Cryptosporidium infection is directly related to the total number of oocysts entering the distribution system in the treated water as represented by the arithmetic mean oocyst density. Monitoring programs based on taking single spot 100‐L volume samples will tend to miss the “all important” high‐count samples and thus underestimate the arithmetic mean and the risk to public health. Spot samples recording 0 oocysts/100 L therefore provide very little reassurance. To detect temporal variation in the form of infrequent high‐count spikes, the Cryptosporidium regulations in the United Kingdom require continuous monitoring of treated water as it leaves the treatment facility.