Factors associated with asymptomatic infection in family members and neighbors of patients with visceral leishmaniasis.

This study analyzed factors associated with asymptomatic Leishmania chagasi infection in family members and neighbors of patients with visceral leishmaniasis (VL). A cross-sectional study was conducted with 361 individuals in the counties comprising Ilha de São Luís (São Luís Island) in Maranhão State, Brazil. The Montenegro skin test (MST) and serology by enzyme-linked immunosorbent assay (ELISA) were performed to detect infection. Odds ratios (OR) and prevalence ratios (PR) and their 95% confidence intervals (95%CI) were estimated by multilevel logistic regression and Poisson regression, respectively. The rates of positive reactions were 71.3% for MST and 9.7% for ELISA. The variable associated with infection according to MST was living in the same household as the index case (PR = 1.36; 95%CI: 1.03-1.78). According to ELISA, the statistically significant variables were: living in the county of Raposa (OR = 3.56; 95%CI: 1.24-10.19) and living in the same household as the index case (OR = 2.70; 95%CI: 1.19-6.08). Family members of individuals with LV are at increased risk of infection. Priority control measures should target these families.