The epidemiology of visceral leishmaniasis and asymptomatic leishmanial infection in a highly endemic Bangladeshi village

We examined the epidemiology of kala-azar and asymptomatic leishmanial infection measured by serologic and leishmanin skin test results in a Bangladeshi community. In a subset, we measured serum retinol, zinc and C-reactive protein (CRP). Kala-azar and seroconversion incidence were 15.6 and 63.1 per 1,000 person-years, respectively. Proximity to a previous kala-azar case increased the likelihood of both kala-azar and asymptomatic infection. Bed net use protected against kala-azar (rate ratio = 0.35, P < 0.01), but not subclinical infection (rate ratio = 1.1, P = 0.82). Kala-azar patients were younger (P < 0.001) and reported lower red meat consumption (P < 0.01) than asymptomatic seropositive individuals. Retinol and zinc levels were lower in current kala-azar patients and those who later developed kala-azar compared with uninfected and asymptomatically infected subjects. The CRP levels were higher in kala-azar patients compared with the other two groups. Low red meat intake and poor zinc and retinol status may characterize a group at higher risk of symptomatic disease.