Estimation of Leishmania spp. infection in asymptomatic people from Muzaffarpur, Bihar, India by antigen-antibody and skin testing

Asymptomatic VL is a concern, considering the risk of transmission in highly endemic areas due to human-to-human transmission. The aim of this study was to report the sero-epidemiological prevalence in Bihar, India, a highly endemic area of VL, using the leishmanin skin test (LST) and the direct agglutination test (DAT). This was a cross-sectional study performed in Muzaffarpur, Bihar, India. Relatives of patients with VL were tested by LST and DAT. Other epidemiological data were evaluated and correlated with tests results. Forty individuals (either previous or current patients), and 109 household contacts were studied. There were 36% of male visceral leishmaniasis family members versus 17.57% of females visceral leishmaniasis family members, thus showing more males with symptomatic disease than females (p<0.01). All visceral leishmaniasis cases had positive DAT tests, but only 37% of past cases were positive on the skin testing. Amongst healthy household contacts, 34% were DAT-positive, whilst 21% were LST-positive. The overall positivity for both assays combined was 44.8% and 23.8% were DAT-positive alone. The finding of high infection prevalence amongst asymptomatic individuals, and the estimation of those at greater risk for overt disease (DAT-positive alone) are important in the development of future disease control policies.