An unknown Trypanosoma species was isolated from an axenic culture of intact skin from a domestic dog captured in Rio de Janeiro, Brazil, which was co-infected with Leishmania (Viannia) braziliensis. Giemsa-stained smears of cultures grown in different media revealed the presence of epimastigotes, trypomastigotes, spheromastigotes, transitional stages, and dividing forms (epimastigotes or spheromastigotes). The highest frequency of trypomastigotes was observed in RPMI (15.2%) and DMEM (9.2%) media containing 5% FCS, with a mean length of these forms of 43.0 and 36.0 mum, respectively. Molecular analysis by sequential application of PCR assays indicated that this trypanosome differs from Trypanosoma cruzi and T. rangeli when specific primers were applied. On the other hand, a PCR strategy targeted to the D7 domain of 24salpha rDNA, using primers D75/D76, amplified products of about 250 bp in that isolate (stock A-27), different from the amplification products obtained with T. cruzi and T. rangeli. This organism differs from T. cruzi mainly by the size of its trypomastigote forms and kinetoplasts and the absence of infectivity for macrophages and triatomine bugs. It is also morphologically distinct from salivarian trypanosomes reported in Brazil. Isoenzyme analysis at 8 loci demonstrated a very peculiar banding pattern clearly distinct from those of T. rangeli and T. cruzi. We conclude that this isolate is a new Trypanosoma species. The name T. caninum is suggested.

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The present study investigated the diagnostic value of polymerase chain reaction (PCR)

A leishmaniose visceral (LV) é uma zoonose, de transmissão vetorial que tem como agente etiológico o protozoário Leishmania (Leishmania) chagasi. No Brasil, esta doença continua sendo um grande desafio nas questões de saúde pública, principalmente pelo potencial endêmico que vem assumindo em vários estados brasileiros 9 . Cães são considerados os principais reservatórios domésticos, sendo monitorados por meio de inquéritos sorológicos, preconizados pelo Ministério da Saúde (MS), que visa a eliminação dos animais sororreatores 9 .O Estado do Rio de Janeiro está classificado como área de transmissão esporádica para LV 9 com casos caninos diagnosticados apenas na capital 1 6 8 , entretanto, recentemente foram relatados casos de leishmaniose visceral canina (LVC) nos municípios de Angra dos Reis e Mangaratiba, demonstrando a expansão da doença para outras regiões do estado 6 . ABSTRACTVisceral leishmaniasis is a zoonosis of public health importance, and dogs represent one of the main problems. This paper describes the first autochthonous case of canine visceral leishmaniasis in the municipality of Maricá. It provides new facts regarding the geographical distribution of Leishmania (Leishmania) chagasi in the State of Rio de Janeiro.

The domestic dog's involvement with different members of the Trypanosomatidae family has been the focus of several studies due to this animal's close proximity to man. Recently this animal has been infected by a new Trypanosoma species (T. caninum), described in Rio de Janeiro and 19 similar isolates were later obtained. The objective of this study was to identify these isolates. All samples were isolated from intact skin cultures and analysed morphologically, by biochemical isoenzyme electrophoresis assays and by several molecular PCR assays. Additionally, anti-Leishmania sp. antibodies were assessed using the indirect Immunofluorescence Antibody Test (IFAT) in all animals. The methodologies employed to identify the isolates, including partial nucleotide sequences of 18S rRNA gene, indicated patterns identical to T. caninum and patterns different from the other species, including T. cruzi and T. rangeli samples. A phylogenetic tree constructed with the partial 18S ribosomal sequence shows that T. caninum is clustered with T. pestanai. Ten (52.6%) animals presented anti-Leishmania sp. antibodies with titres varying from 1:40 to 1:320. Thus, the hypothesis that this protozoan has disseminated among the dogs in Rio de Janeiro must be considered. The importance of a correct diagnosis in those animals and the possible consequences in the areas where visceral leishmaniasis is found are discussed here.