Acquisition of serum antibody to Norwalk Virus and rotavirus and relation to diarrhea in a longitudinal study of young children in rural Bangladesh.

Serum antibodies to Norwalk virus and to rotavirus were measured during longitudinal studies of infectious diseases and nutrition in rural Bangladesh. Initially, the prevalence of antibody to Norwalk virus was 7% in children younger than six months and increased to 80% in children two to five years of age. The incidence of titer increases was highest in one- and two-year-olds and in children who had low or undetectable levels of antibody. Some Norwalk virus infections appeared to result in diarrhea. Nearly all children had serum antibodies to rotavirus at the beginning of the study; however, children with the lowest levels of antibody to rotavirus had the greatest risk of rotavirus diarrhea. Over half of the children had a fourfold increase in titer of antibody to rotavirus during the year, and 7% had increases in two of the three study periods during the year. Most increases in titer of antibody to rotavirus appeared to result from subclinical infections.