Natural infection of Didelphis aurita (Mammalia: Marsupialia) with Leishmania infantum in Brazil.

BACKGROUND: The opossum Didelphis have been considered as natural hosts of Leishmania parasites in the New World, suggesting an important role in the epidemiology of Visceral Leishmaniasis (VL). Among six extant species that belong to the genus Didelphis, only two (D. marsupialis and D. albiventris), have been mentioned as natural hosts of Leishmania infantum in Brazil and Colombia. In the present paper, it is reported for the first time, the observation of intracellular parasites (amastigotes) in tissues of Didelphis aurita naturally infected with Leishmania infantum in Brazil. We also discuss some aspects associated to the relationship between L. infantum and the geographical distribution of some species of the genus Didelphis. METHODS: The opossums studied were caught by wire traps (Tomahawk) in Barra de Guaratiba, a peri-urban area in Rio de Janeiro. The opossums were killed with an overdose of Thiopental sodium.At necropsy, macroscopic alterations were examined and samples from liver, spleen, lymph nodes, ear, abdominal skin, scent glands and bone marrow were collected for parasitological and molecular diagnoses. RESULTS: Forty-eight opossums were captured in an AVL endemic region, 30 being caught in a mangrove area and eighteen animals in a forest area near to some residential-yards. Among the thirty opossums trapped in the mangrove area, all of them were negative by both imprint and sera samples assayed on Dipstick Tests, that is a test based on a combination of protein-A colloidal gold conjugate and rk39 Leishmania antigen to detect anti-Leishmania antibody in serum or plasma. At the macroscopic examination one out of eighteen opossums, caught close to the forest, presented alterations compatible with spleen hypertrophy and three were positive by Dipstick Tests (16.6%) and presented amastigotes in the spleen and in one of them, the parasites were also observed in a submandibular lymph node. Leishmania infantum infections were confirmed through dot blot hybridization using a L. infantum-specific biotinylated probe. CONCLUSIONS: In the present paper we present the first report of amastigotes in the tissues of Didelphis aurita (Mammalia: Marsupialia) naturally infected with Leishmania infantum. We also attempt to claim the particular role of some opossum species as hosts of Leishmania infantum, contributing at least in part on the description of potential sylvatic reservoirs.

Canine leishmaniasis in Brazil: serological follow-up of a dog population in an endemic area of american visceral leishmaniasis.

We performed a serological, clinical, and parasitological follow-up of a dog population in an endemic area of American Visceral Leishmaniasis estimated by indirect immunofluorescent assay (IFA) and western blot (WB). After twelve months, the results obtained from IFA demonstrated that 50% were seropositive and two serological profiles were observed: the first one ranging from 1/40 to 1/80 and the second >/=1/160. By WB, it was observed that the same percentage and sera from positive dogs presented the recognition of the peptides of 29 and 32 kDa up to 8 months before IFA serum conversion. Among the positive dogs, all the sera from symptomatic ones with tissue parasitism recognized the peptide of 68.5 kDa. Our results suggest the need of modifications in the control measures regarding the elimination of the dogs. They also corroborate the high sensitivity and specificity of western blot in the diagnosis of canine leishmaniasis, suggesting the possibility of its association with IFA.

The first record of American visceral leishmaniasis in domestic cats from Rio de Janeiro, Brazil.

This paper is the first to report visceral leishmaniasis in domestic cats (Felis catus domesticus) from an endemic area in Rio de Janeiro state, Brazil. A relatively high seroprevalence of 25% was observed although none of them have presented any symptom. Our results support the observation of previous authors, suggesting that cats may be considered as alternative domestic hosts of visceral leishmaniasis and should be included in serological investigations performed in endemic areas.