Competence of the human host as a reservoir for Leishmania chagasi

The failure of control programs for visceral leishmaniasis (VL) that depend on elimination of infected dogs suggests that other reservoir hosts may pa rticipate in the transmission cycle. To determine whether persons infected with Leishmania chagasi can infect the vector sand fly, laboratory-reared L utzomyia longipalpis were allowed to feed on Brazilian subjects with active , cured, and asymptomatic VL and on asymptomatic residents of houses of per sons with active VL, Of 3747 insects that had fed, 26 acquired infection fr om 11 of the 44 persons with active VL, but none acquired infection from th e 137 asymptomatic persons. Among persons <4 years old with active VL, a hi story of diarrhea and higher peripheral blood neutrophil counts were indepe ndent predictors of infectivity, Further experiments using larger numbers o f insects are necessary to evaluate the reservoir competence of persons wit h asymptomatic infections, who represent a large segment of the population of several Brazilian cities.