Leishmaniasis in Brazil: IX. Considerations on the Leishmania braziliensis complex:—Importance of sandflies of the genus Psychodopygus (mangabeira) in the transmission of L. braziliensis braziliensis in North Brazil

Abstract

At least 3 different parasites may produce cutaneous leishmaniasis in man in Brazil. Leishmania mexicana amazonensis is widely distributed and very common in wild animals, but rarely infects man because the vector is not anthropophilic. L. braziliensis guyanensis and L. braziliensis braziliensis have highly anthropophilic vectors and are thus the major causes of the disease in man. Infections with Leishmania b. braziliensis are described in 17 persons from an endemic area in the Serra dos Carajás, Pará, north Brazil. A nearby Indian tribe (Xikrín) was examined and leishmanin skin-tests carried out on 116 individuals. No evidence of past or present infection was found, but strong positive reactions were noted in 83·9% adult males, 38·8% adult females, 14·3% male children and 4·8% female children. A total of 2,701 man-biting and rodent-biting sandflies were dissected and the guts examined for flagellates. Promastigotes were found in 3 out of 1,656 Psychodopygus wellcomei, 2 out of 175 Ps. paraensis and 1 out of 127 Ps. amazonensis. Hamsters inoculated with promastigotes from one Ps. wellcomei developed a typical L. b. braziliensis infection. The importance of sandflies of the genus Psychodopygus is stressed: Ps. wellcomei is of particular importance due to its tendency to bite man during the day and the fact that it is attracted to both man and rodents in large numbers. Nearly all the sandflies were caught at ground level. The absence of a large, arboreal population of man-biters suggests that the reservoir-hosts of L. b. braziliensis are likely to be terrestrial or frequently coming to the ground.