Visceral leishmaniasis in southeastern Nepal: a cross-sectional survey on Leishmania donovani infection and its risk factors.

OBJECTIVE To document the frequency of Leishmania donovani infection at community level in a highly endemic region in southeastern Nepal, and to assess socioeconomic and environmental risk factors. METHODS A random cross-sectional population survey was held in two visceral leishmaniasis (VL) foci in Morang District in April to May 2003, enrolling individuals 2 years or older and residing in the endemic area for at least 12 months. Leishmania infection was defined as a direct agglutination test (DAT) titre equal to or higher than 1:3200. Risk factors were identified by logistic regression. RESULTS The direct agglutination test was positive in 7.5% (95% CI: 5.1-10.8) and the leishmanin skin test (LST) in 13.2% (95% CI: 9.9-17.2) of the 373 study participants. No case of current kala-azar was found, but 5.1 % (95% CI: 3.1-7.8) reported having suffered from VL. Independent risk factors for Leishmania infection were proximity of the house to ponds [odds ratio (OR) 3.7, 95% CI: 1.6-8.5], family size (OR 4.4, 95% CI: 1.6-12.6), age > or =15 years (OR 5.5, 95% CI: 1.2-25.0) and house constructed in mud (OR 3.0, 95% CI: 1.1-7.6). Bednets, not impregnated and in poor condition, were used by 95.2% (95% CI: 92.3-97.0) of the population, but did not show any protective effect. CONCLUSION This study shows that there is a serious problem of transmission of VL in this area of Nepal. The risk factors identified are linked with the socioeconomic level and the environment. The population would benefit from a community intervention to improve the environmental and housing conditions in the villages.