THE ENTEROVIRUS TEST IN THE ASSESSMENT OF RECREATIONAL WATER-ASSOCIATED GASTROENTERITIS

This study reports the results of a series of analyses designed to ide ntify possible mathematical relationships between the numbers of fecal streptococci vs the numbers of enteroviruses present (as measured by the enterovirus assay) in marine recreational waters in order to indir ectly assess the relationship between enteroviral densities and subseq uent risk of gastroenteritis among bathers exposed to marine waters co ntaminated with domestic sewage. A database consisting of 2066 paralle l fecal streptococci and enterovirus enumerations taken from 416 diffe rent marine water locations throughout the United Kingdom was used in the analyses. Polychotomous logistic regression was used to model the probabilities of zero enterovirus, a possible infectious dose and a pr obable infectious dose of enterovirus being present over increasing fe cal streptococci densities. The results of the polychotomous logistic regression analyses showed that the probability of the absence of ente rovirus (i.e., zero enteroviruses being present) remained higher than the probability of the presence of either a possible or probable infec tious dose in 101 of seawater up to a fecal streptococci density of 10 00/100 mi of sample (actual estimated probabilities for the three grou pings of enterovirus densities described above, at a fecal streptococc i density of 1000 equaled 0.44, 0.44, and 0.12, respectively). In addi tion, the probability of zero enteroviruses being present remained hig her than the probability of one or more enteroviruses being present in 101 of seawater up to a fecal streptococci density of 450/100 mi of s ample. Since previously published epidemiological studies have shown a n excess risk of gastroenteritis to occur among bathers exposed to as few as 32 fecal streptococci per 100 mi of sample, these results sugge st that the actual viruses enumerated by the enterovirus assay are not etiologically related to recreational water-associated gastroenteriti s. Since gastroenteritis has been the most consistently reported bathi ng water associated illness, these findings suggest the enterovirus as say to be of limited use in assessing marine recreational water qualit y given the increasing tendency to formulate water quality standards b ased on increased risk of gastroenteritis among bathers relative to no n-bathers. Copyright (C) 1996 Elsevier Science Ltd