Serum, fecal, and breast milk rotavirus antibodies as indices of infection in mother-infant pairs.

Sixty-eight mother-infant pairs were followed for 12-17 months after birth. Rotavirus infections in children were detected by EIA of weekly fecal antigen and anti-rotavirus IgA levels, by EIA of anti-rotavirus IgG in sera at birth, 6, or 12-17 months of age, and by anti-rotavirus EIA IgA and neutralizing antibody (NA) in monthly samples of maternal breast milk. Primary rotavirus infection was detected in 26 children (in 15 [58%] by fecal excretion, 12 [46%] by IgG seroconversion, and 22 [85%] by elevations of IgA anti-rotavirus antibodies [IgA coproconversion] in consecutive fecal specimens). Rotavirus "challenge" was detected by rises in levels of NA in breast milk in 9 (47%) of 19 mothers, including 5 (26%) from pairs in which there was no other evidence of rotavirus infection. Reinfections were detected in 2 children by rotavirus excretion and in 4 by coproconversion. IgA coproconversion is the most sensitive technique for detection of symptomatic and asymptomatic rotavirus infection in young children.