Leishmaniose tegumentar (LT): zoonose de roedores silvestres (Oryzomys goeldii Thomas) na Amazônia (Publicado originalmente em 1966)

Abstract

This 6th note relates some new observations on Oryzomys’ leishmaniasis and presents studies of the Phlebotomus from Utinga forest. Finally, some comments on probable meaning of Oryzomys’ leishmaniasis are made. From August 1963 to Apri1 1964, from 121 Oryzomys examined, 24 (19.8%) were found positive. From May 1964 to February 1966, from 213 (Oryzomys examined, only ten (4.7%) were found infected. So, the prevalence has falled more than four times. The reasons of this fact are probably the following: First, the removal from the focus of 13 infected Oryzomys (accidental death, histopathological studies and the beginning of laboratory breeding). Indeed, that represents the elimination of more than a half of the reservoirs met till April 1964. In a second place, the removal of thousands of Phlebotomus from the area by systematic captures. On the other hand, it is possible that some light lesions of Oryzomys’ tail escaped at inspection. However, it is possible too, that the above mentioned reasons are not so significative as we intend to understand them, since from December 1965 to February 1966 we have found three infected Oryzomys. As we have mentioned, captures of Phlebotomus were made periodically. From 1068 Phlebotomus, captured in 1963 and 1964, belonging to 15 species, 68.6% were P. antunezi e P. damascenoi. In 1965, from May to December systematic mouthy captures were made, with a mean of 18 captures by month. From a total of 4736 specimens, belonging to 24 species, 38.1% were P. rorotaensis, 21.7% were P. antunezi and 16.2% were P. damascenoi. The Oryzomys’ infection conditions in Utinga forest shows very clearly its zoonotic character. Probably, other rodents integrate this wild cycle in other areas of Amazonia and in other forest regions of the country. Naturally, according to infected region different species of Cricetidae reservoirs and Phlebotomus transmitters are integrated in that wild cycle. Man – so sensitive to leishmaniasis – became infected when penetrates in zoonotic area interfering in that wild cycle. After the forest overthrown to settlement and, consequently, the wild animals escape, the rural leishmaniotic foci were established and later suburban and urban foci too. In these foci, with domiciliary and peri-domiciliary Phlebotomus transmitters, the dog and, probably, also man appear as secondary reservoirs. So, in the leishmaniasis epidemiology we have two cycles: The wild or zoonotic and the rural or anthroponotic. The latter can be controlled by domiciliary and peridomiciliary expurgation with residual-acting insecticides. But obviously, it is impossible to control the zoonotic foci. It is a permanent menace to those who are obliged to visit the forests. Individual protection measures must be employed. The development of better techniques for disposal of efficient vaccines must be promoted.