Longitudinal seroepidemiologic study of visceral leishmaniasis in hyperendemic regions of Bihar, India.

We conducted a seroepidemiologic study of visceral leishmaniasis (VL) in hyperendemic communities in Bihar, India, to determine its seroprevalence. A direct agglutination test (DAT) and rK39 antigen strip test were used as serologic tests. Capillary blood samples were collected on filter papers from 870 healthy persons (574 and 296 from households with or without VL, respectively). Of these persons, 230 (26.43%) were positive by DAT (titer > or =1:1,600) and 120 (13.79%) were positive by the rK39 antigen strip test. During a two-year follow-up, 25 persons developed VL; 1 and 8 persons were positive by the rK39 strip test and DAT, respectively, and 1 was positive by both tests. Fifteen (2.57%) persons who were seronegative at baseline also developed VL. Disease occurred more among persons living in the same household (24 of 25). However, there was no significant difference in disease conversion among children (5-15 years of age) and adults (> 15 years of age). Seropositivity among asymptomatic persons is not a predictor for development of VL.