Human asymptomatic infection in visceral leishmaniasis: a seroprevalence study in an urban area of low endemicity. Preliminary results.

Many aspects of the human asymptomatic visceral leishmaniasis (VL) remain not elucidated, and moreover, almost all the data come from highly endemic areas. The recent appearance of American VL (AVL) in the northeastern region of the state of São Paulo, Brazil, offered a good opportunity for further understanding. We present the preliminary results from a seroprevalence study on AVL in humans in Araçatuba, São Paulo. This was a cross-sectional survey on a random sample of the population (one-stage simple random sampling) in two areas, using rK39 dipstick tests. The sex ratios and age distributions in the two areas were comparable. Detectable antibodies were found in 23 subjects (20%) in area A1 and in 6 subjects (4.8%) in area A2. There was no significant difference in age distribution of seropositivity between the areas. We observed a difference in asymptomatic infection rates between the two areas, possibly associated with socioeconomic levels and transmission intensity.