ELISA with recombinant rKRP42 antigen using urine samples: a tool for predicting clinical visceral leishmaniasis cases and its outbreak.

We reported a highly sensitive and specific enzyme-linked immunosorbent assay (ELISA) that detects immunoglobulin G (IgG) in urine using rKRP42 antigen for the diagnosis of visceral leishmaniasis (VL). The ELISA was applied to study chronological change in antibody titers in five study areas in Rajshahi district, Bangladesh. A total of 585 subjects without a past VL history were examined at least three times in the 30-month follow-up period; of these subjects, 137 (23.4%) subjects became ELISA-positive at least one time during the study. Among the positive cases, 40 (29.2%) subjects developed clinical VL, and 31 (77.5%) of these subjects showed IgG titers of ≥ 1,000 U more than one time in the study period. Considering only the first ELISA results, 22 subjects with IgG titers of ≥ 1,000 U could be found, and 21 (95.5%) of these subjects turned out to be clinical cases. The high urinary IgG titers (≥ 1,000 U) will help predict possible clinical VL cases and thus, identify an outbreak in its earlier stage.