Prevalence and levels of filaria-specific urinary IgG4 among children less than five years of age and the association of antibody positivity between children and their mothers.

An enzyme-linked immunosorbent assay (ELISA) to detect filaria-specific urinary IgG4 was tested in samples from 203 children less than five years old and their parents (165 mothers and 127 fathers) in Sri Lanka. There were four IgG4-positive children within 58 days after birth, suggesting the transfer of the antibody from mothers. No positive children were found between days 65 and 417. After day 1,000, the number of the positive individuals and the level of IgG4 increased quickly. The children of urinary IgG4-positive parents showed a higher IgG4 positive rate than those of negative parents. The children of positive mothers had a higher prevalence than those of negative mothers, whereas, the positivity of the fathers was not associated with that of their children. Collecting urine samples was easy to perform and well accepted because of its non-invasiveness. The ELISA will be useful for monitoring filarial infections in very young children, who are a sentinel population for evaluating the intensity of filariasis transmission and effectiveness of control measures.