We determined the presence or absence of rotavirus
antigen by the
enzyme-immunoassay in 126 fecal specimens obtained from infants with acute
gastroenteritis, and also measured
IgA antibody titers against rotavirus in stool samples. Rotavirus-positive specimens amounted to 72. Thirty-five specimens in 126 stool samples were found to contain the
IgA antibody against rotavirus. The
IgA antibody against rotavirus was detected in 21% and 44% of fecal specimens obtained from age groups of less than 3 years and 3 years or more, respectively, showing a significant difference between these 2 groups. The geometric mean titer of specific
IgA antibody was also higher in the latter group than in the former. This specific
IgA antibody was detected in 32% and 22% of boys and girls, respectively, showing a tendency of high incidence among boys. The detection rate of specific
IgA antibody was significantly higher in rotavirus-negative fecal specimens (41%) than in rotavirus-positive fecal specimens (18%). As for infants having the rotavirus
antigen in their feces, their symptoms were severe in many of the infants at the age of less than 3 years, while many of the infants at the age of 3 years or more only had mild symptoms. There was a significant difference between the 2 age groups. When these infants were analyzed according to the presence or absence of specific
IgA antibody in their feces, no difference in scores of severity of clinical symptoms was seen between the 2 groups. However,
IgA antibody-negative infants more frequently had
fever, over 39 degrees C and significantly more developed whitish and watery stool in comparison with
IgA antibody-positive infants.(ABSTRACT TRUNCATED AT 250 WORDS)