Leishmaniasis in Brazil XXI: visceral leishmaniasis in the Amazon Region and further observations on the role of Lutzomyia longipalpis (Lutz & Neiva, 1912) as the vector

Abstract

Further evidence is presented incriminating the sandfly Lutzomyia longipalpis as the vector of Leishmania chagasi, the causative agent of American visceral leishmaniasis, in the Amazon Region of Brazil. During an outbreak of the disease in Santarém, Pará State, this insect was shown to be the only species of sandfly consistently present in and around the patient's homes, where it often occurred in very large numbers. Of 491 specimens dissected, 35 (7.14%) proved to be infected, and isolates of L. chagasi were made from 16 of 27 of these sandflies following the inoculation of the promastigotes into hamsters. Finally, the parasite was transmitted to four other hamsters which had been subjected to the bites of large numbers of wild-caught Lu. longipalpis. Isolates of Leishmania from Lu. longipalpis captures in Santarém, and in another focus of visceral leishmaniasis on the Island of Marajó, Pará, have been shown to be biologically and biochemically indistinguishable from the parasite infecting man, dogs and foxes in Pará, and from stocks obtained from man elsewhere in Brazil (Bahia and Ceará States).

São apresentadas novas evidências, incriminando o flebotomíneo Lutzomyia longipalpis como vetor de leishmaniose visceral na Região Amazônica do Brasil. Durante um surto da doença ocorrido recentemente em Santarém, Estado do Pará, verificou-se ser essa a única espécie de flebotomíneo constantemente presente dentro e nos arredores das casas dos pacientes, usualmente em grande número. Protnastigotos foram encontrados em 3S (7, 14%) de 491 fêmeas de Lu. longipalpis dissecadas, tendo o parasita sido isolado de 16 desses insetos, através da inoculação dos flagelados em hamsters, e transmitido a quatro outros hamsters pela picada de espécimens infectados em natureza. O estudo em Santarém, e de outro foco de leishmaniose visceral registrado na Ilha do Marajó, Pará, mostrou que os isolamentos de Leishmania obtidos de Lu. longipalpis, do homen, de raposas, e de cães, são biologicamente e bioquimicamente indistinguíveis.