Potential spectrum of etiological agents of viral enteritis in hospitalized infants.

Fecal specimens were obtained from 1,160 infants and young children with acute nonbacterial gastroenteritis over a period of 2 years. A total of 100 specimens were obtained from age-matched asymptomatic controls. The specimens were examined for the presence of viruses by electron microscopy. Viruses or virus-like particles frequently associated with enteritis were detected in 27% (314 of 1,160) of the symptomatic patients. No viruses or virus-like particles were detected in the 100 control subjects. Rotavirus was detected in 73% (230 of 314) of the virus-positive samples. The mean age of rotavirus-positive patients was 11.5 months, although the patients ranged in age from 2 weeks to 5 years. Of the symptomatic patients, 45 (14%) exhibited small virus-like particles (15 to 40 nm) in the feces in the absence of any other detectable pathogen. Some of the virus-like particles observed in these patients appeared to be similar to astrovirus, and some appeared to be similar to the Otofuke agent or possibly minireovirus. Significantly, however, the mean age of infants with enteritis from whom these small virus-like particles were recovered was 4.5 months (range, 10 days to 19 months). Our findings confirmed the already-known fact that rotaviruses constitute the most important cause of viral enteritis in young children. In addition, small viruses may be an important cause of gastroenteritis in infants under 5 months of age.

Development of serum and intestinal antibody response to rotavirus after naturally acquired rotavirus infection in man.

The temporal characteristics of the response of rotavirus specific IgM, IgG, IgA in serum and secretory antibody in feces to rotavirus were studied in 77 hospitalized patients with rotavirus induced gastroenteritis. The response in serum was characterized by the sequential appearance of rotavirus specific IgM, IgG, and IgA antibody. The IgM antibody appeared to be higher in the acute phase of the disease and was subsequently replaced by the IgG and IgA antibodies. However, the titers of IgG rotavirus antibody in convalescent specimens of serum were found to be statistically significantly lower in patients with severe or prolonged rotavirus infection than in specimens from subjects with mild or moderate disease. Most fecal specimens collected during both the acute and convalescent phase of illness contained virus specific secretory IgA. Higher concentrations of antibody were measured in convalescent samples from patients with prolonged diarrhea and virus shedding. These observations suggest a possible relationship between the severity of rotavirus infection and the nature of systemic and secretory antibody response.