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The objective of this work was to develop and validate a dose-response model for E. coli O157:H7. Such a model could be used to formulate criterion for finished water pathogen concentrations, given a policy-derived acceptable risk criterion (i.e., 1/10,000 infections per person per year). Pai et al studied the pathogenesis of diarrheal disease due to E. coli O157:H7 in infant New Zealand white rabbits. The rabbits were orally administered known doses of E. coli O157:H7. After inoculation, the animals were observed daily for diarrhea, and infection confirmed via a post-mortem examination of the intestine. The beta-Poisson model based on animal studies adequately describes the human morbidity risk of E. coli O157:H7. The exponential model did not provide an acceptable fit to the animal data. The beta-Poisson model not only provided an acceptable fit, but also showed a statistically significant improvement in fit over the exponential model. The median infectious and lethal doses were 600,000 and 8,000,000 organisms, respectively. However, at an administered average dose of one organism, the models suggest probabilities of infection and mortality of 2.6 u10-[6] and 2.6 u10-[7], respectively.

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Edition: Vol. - No. Published: 09/29/1999 Number of Pages: 2 File Size: 1 file , 67 KB