Leishmaniasis in Brazil: I. Observations on enzootic rodent leishmaniasis—incrimination of lutzomyia flaviscutellata (mangabeira) as the vector in the lower amazonian basin

Abstract

During observations on a focus of enzootic leishmaniasis of rodents in the Utinga Forest, Belém, Pará, Brazil, active infections were encountered in 16 (17·98%) of 89 Oryzomys capito examined. Cutaneous lesions were restricted to the tails of these animals, and spontaneous recovery leaves characteristic scarring. Taking such scars into account, it is estimated that as many as 70% of the Oryzomys population may experience infection at some time during their lives. Leishmania were isolated from 3 specimens of Proechimys guyannensis captured in the same forest area. In addition to obvious lesions on the tail and foot, parasites were isolated from apparently normal ear tissue. The strains of Leishmania from Oryzomys and Proechimys appear to be identical. Insect traps were baited with Oryzomys, Proechimys and other rodents. During a period of 4 months they captured 2,774 phlebotomine sandflies, of which 2,731 were Lutzomyia flaviscutellata Mangabeira. In contrast, only 5 specimens (0·69%) of Lu. flaviscutellata were encountered among 724 sandflies caught of human bait during the same period, in the same area. Leptomonads were found in 8 of 2,706 Lu. flaviscutellata dissected (0·29%). Inoculation of these flagellates into hamsters produced typical leishmanial lesions in 6 cases. We conclude that Lutzomyia flaviscutellata is the major vector of the Leishmania sp., among Oryzomys and Proechimys in the Utinga Forest area of the Lower Amazon Region. Similarities are noted between this parasite of Brazilian rodents and Leishmania mexicana of rodents and man in Central America.