Asymptomatic infection in family contacts of patients with human visceral leishmaniasis in Tres Lagoas, Mato Grosso do Sul State, Brazil

The Brazilian city of Tres Lagoas, Mato Grosso do Sul State, has experienced an urban outbreak of visceral leishmaniasis since 2000. In 2002, due to the increase in the number of cases, 46 families with cases of visceral leishmaniasis were studied to verify the prevalence of asymptomatic infection in household contacts. Indirect immunofluorescence and ELISA showed a 36.4% positive infection rate. There were no cases of symptomatic disease among these contacts. There was no statistically significant difference in gender or age. Median age was 21 years, and the 10-19-year age bracket was the most heavily affected (23%). As for family characteristics, no differences were observed in schooling or family income; most families (58.7%) owned their homes, which were built of masonry (97.8%) and had adequate infrastructure. All the families reported what were probably phlebotomine sand flies in the peridomicile. In conclusion, asymptomatic visceral leishmaniasis infection is frequent and occurs in both males and females, regardless of age.