Presence and gradual disappearance of filaria-specific urinary IgG4 in babies born to antibody-positive mothers: a 2-year follow-up study.

A total of 14 Sri Lankan pregnant women, who were anti-Brugia pahangi urinary IgG4 positive, and their 14 newborn babies were followed up for the urinary antibody for 2 years by enzyme-linked immunosorbent assay. Eight babies showed positive IgG4 reaction, at least once within 4 months after birth. Urinary antibody titers of mothers and their babies measured around the perinatal period showed a significant positive correlation, suggesting that baby's IgG4 was transferred from the mother through the placenta. The IgG4 decreased gradually and became negative in all positive babies by day 339.3 after birth. The present result provides a basis to judge if a positive urine ELISA test among babies is due to a new filarial infection.