The frequency of a Norwalk-like pattern of illness in outbreaks of acute gastroenteritis.

TLDR

The study reviewed 642 acute gastroenteritis outbreaks to estimate how many matched Norwalk‑like virus infection criteria. The authors applied criteria of negative bacterial cultures, 12–60‑hour illness, ≥50 % vomiting, and 24–48‑hour incubation to identify 54 Norwalk‑like outbreaks, of which 14 were tested for virus. Among the identified outbreaks, 23 % were waterborne, 4 % foodborne, 67 % nursing home, 60 % summer camp, and 28 % cruise ship; 71 % of tested outbreaks had Norwalk‑like virus serology, supporting that Norwalk‑like viruses are a major cause of acute gastroenteritis outbreaks and that antibody testing is diagnostically valuable.

Abstract

Records of 642 outbreaks of acute gastroenteritis were reviewed to determine the proportion of outbreaks that were clinically and epidemiologically consistent with Norwalk-like virus infection. Using as our criteria stool cultures negative for bacterial pathogens, mean (or median) duration of illness 12-60 hours, vomiting in greater than or equal to 50 per cent of cases, and, if known, mean (or median) incubation period of 24-48 hours, we found that 23 per cent of waterborne outbreaks, 4 per cent of foodborne outbreaks, and 67 per cent, 60 per cent, and 28 per cent of outbreaks in nursing homes, in summer camps, and on cruise ships, respectively, satisfied the criteria for Norwalk-like pattern. Of 54 outbreaks that satisfied the criteria for Norwalk-like pattern, 14 were investigated for virus etiology. Ten of these (71 per cent) yielded serologic evidence of Norwalk-like virus infection. Norwalk-like viruses are probably an important cause of outbreaks of acute gastroenteritis. Investigation for Norwalk virus antibody in outbreaks that are clinically and epidemiologically consistent with Norwalk-like virus infection is likely to yield diagnostically useful results.