Roedores silvestres (Oryzomys goeldii) da Amazônia com infecção natural por Leishmania: primeira nota (Publicado originalmente em 1964)

Abstract

In 1937, Chagas e coll. examining hundreds of forest rodents from Amazonia, have found “suspected” forms of Leishmania in Proechymys. This and other wild rats were found with natural leishmaniasis in Panama (Hertig e coll., 1957 - 59). Lainson & Strangways-Dixon (1962) reported the occurrence of spontaneous leishmaniasis in several wild rodents (Ototylomys, Peromyscus and Heteromys) from British Honduras. In 1963, dr. Lainson visited the Instituto Evandro Chagas, at Belem (State of Para) and mentioned his paper on the matter. So, immediately, two wild rats (Oryzomys) captured in the Utinga forest in the neighbourhood of Belem, have been found naturally infected with leishmaniae. A wide land of Utinga forest was subdivided in smaller areas in which were distributed traps for the capture of the rodents for arboviruses studies* . From 111 Oryzomys examined, 24 have been found infected with leishmaniae until April, 1964. The leishmaniasis is apparently a zoonosis of these rodents. From 24 specimens infected, seven died or were sacrificed, furnishing material for anatomopathological studies. Nineteen other Oryzomys were considered suspected of infection, but the direct examination was negative. If cultures were made probably some more would be positive. Hundreds of other rodents (Proechymys, Nectomys, Caluromys) were examined with negative results. Other rodents and marsupials were also considered “suspected” but their examination was negative. From 24 positive Oryzomys, 16 (66.7%) were found infected between December 1963 and March 1964. After the first two positive Oryzomys, others specimens were found free of infection. Subsequently, these animals became positive; 56.2% between 40 and 70 days and 37.3% between 87 and 115 days. As described by Lainson e Strangways-Dixon (1962) in wild rats from British Honduras, the lesions of the tail of Oryzomys were very characteristic: whitish, squamous and superficial erosions. But in sections, edema and histiocytes and mononuclear cells infiltration penetrates deeply provoking myositis foci. Histiocytes filled with leishmaniae appear side by side in large areas. Material from the lesions of the tail suspended in saline was injected in hamsters and mice. Those animals inoculated subcutaneously developed nodular lesions with numerous parasites. Attempt of transmission by direct contagion among the Oryzomys was negative until 80 days. Smears and sections of hundreds of sandflies captured in the Utinga forest were examined with negative results for leptomonads. Triturated of a great number of these psicodidae in saline was injected in the nose of hamsters which continue in observation after 50 days apparently free of infection.