Prevalence and serotype specificity of rotavirus antibodies in different age groups of Ecuadorian infants.

The age-specific prevalence of antibody to rotavirus was studied in 1404 Ecuadorian children enrolled in a national nutrition and health survey. ELISA and neutralizing antibody analysis showed evidence for primary rotavirus infection in 6- to 12-month-old children, who showed also a more-than-threefold increase in significant diarrheal episodes in comparison with infants less than 6 months old. At this age, 56% of the sera with neutralizing antibody were monospecific. With increasing age a gradual decrease in prevalence of monospecific sera, to 10% in 5-year-old children, was observed. Monospecific sera were directed in decreasing frequency against serotypes 4 (56%), 3 (20%), 2 (14%), and 1 (10%). Serotype 4-specific antibody was acquired at an earlier age than were antibodies to the other serotypes, and 91% of sera with dual specificity neutralized serotype 4, whereas only 2% of sera that neutralized three serotypes failed to neutralize serotype 4.