The TcI and TcII Trypanosoma cruzi experimental infections induce distinct immune responses and cardiac fibrosis in dogs

Trypanosoma cruzi infection may be caused by different strains with distinct discrete typing units (DTUs) that can result in variable clinical forms of chronic Chagas disease. The present study evaluates the immune response and cardiac lesions in dogs experimentally infected with different T. cruzi strains with distinct DTUs, namely, the Colombian (Col) and Y strains of TcI and TcII DTU, respectively. During infection with the Col strain, increased levels of alanine aminotransferase, erythrocytes, haematocrit and haemoglobin were observed. In addition, CD8+ T-lymphocytes isolated from the peripheral blood produced higher levels of interleukin (IL)-4. The latter suggests that during the acute phase, infection with the Col strain may remain unnoticed by circulating mononuclear cells. In the chronic phase, a significant increase in the number of inflammatory cells was detected in the right atrium. Conversely, infection with the Y strain led to leucopoenia, thrombopoenia, inversion of the ratio of CD4+/CD8+ T-lymphocytes and alterations in monocyte number. The Y strain stimulated the production of interferon-γ by CD4+ and CD8+ T-lymphocytes and IL-4 by CD8+ T-cells. In the chronic phase, significant heart inflammation and fibrosis were observed, demonstrating that strains of different DTUs interact differently with the host.

First description of autochthonous canine visceral leishmaniasis in the metropolitan region of Vitória, State of Espírito Santo, Brazil / Primeira descrição de leishmaniose visceral canina autóctone na Região Metropolitana de Vitória, Estado do Espírito Santo, Brasil

INTRODUCTION: We investigated autochthonous canine visceral leishmaniasis (CVL) in the metropolitan region of Vitória (MRV), an area in which a human case was previously reported. METHODS: Serological, parasitological, and molecular tests were performed in 201 dogs. RESULTS: Twenty-six (13%) and 12 (6%) dogs were identified as positive using in-house enzyme-linked immunosorbent assay (ELISA) and rK39 tests, respectively. Two dogs had a positive culture for Leishmania chagasi, and 4 were polymerase chain reaction (PCR)-positive for Leishmania spp. One positive dog belonged to the aforementioned patient. CONCLUSIONS: Although the responsible vector was not found, our results provide evidence of autochthonous CVL in the MRV, a non-endemic area for VL.

INTRODUÇÃO: Descrevemos um foco de leishmaniose visceral canina (LVC) autóctone na Região Metropolitana de Vitória (RMV) onde um caso humano foi registrado anteriormente. MÉTODOS: Testes sorológicos, parasitológicos e moleculares foram realizados em 201 cães. RESULTADOS: Vinte e seis (13%) e 12 (6%) foram positivos para um teste ELISA in house e rK39, respectivamente. Dois cães apresentaram cultura positiva para Leishmania (Leishmania) chagasi e quatro PCR positivo para Leishmania spp. Um dos cães positivo pertencia ao paciente supracitado. CONCLUSÕES: Embora o vetor não tenha sido encontrado, nossos resultados fornecem evidências da LVC autóctone na RMV, área não-endêmica para leishmaniose visceral.

Autochthonous canine visceral leishmaniasis in a non-endemic area: Bom Sucesso, Minas Gerais State, Brazil

The article begins by describing a dog with characteristic symptoms of visceral leishmaniasis. A serum sample from this animal was positive by indirect immunofluorescence (IIF) performed in anti-Leishmania total IgG in 1999. Tissues from the same dog were also positive by polymerase chain reaction (PCR) in 2004, identifying Leishmania DNA in the cerebellum, liver, kidney, and intestine. This is the first report of a dog with autochthonous visceral leishmaniasis in the county of Bom Sucesso, Minas Gerais State, Brazil. The finding of this IIF-positive dog led to a canine visceral leishmaniasis epidemiological investigation in the county. The investigation was conducted from March 1999 to December 2005. IIF was positive for Leishmania in 22 (3 percent) of 734 examined dogs. Among the 22 IIF-positive dogs, six presented characteristic symptoms of canine visceral leishmaniasis. The results of this epidemiological investigation were sent to local and State public health authorities, requesting visceral leishmaniasis control and preventive measures to interrupt transmission of the disease and avoid the occurrence of human cases.

O presente trabalho descreve inicialmente um cão com sintomas característicos de leishmaniose visceral. Amostra de soro desse cão foi positiva por imunofluorescência indireta (IFI) conduzida no IgG total anti-Leishmania em 1999. Além disso, tecidos desse cão foram positivos por reação em cadeia pela polimerase (PCR) conduzida em 2004, identificando DNA de Leishmania no cerebelo, fígado, rim e intestino. Esta é a primeira vez que um cão com leishmaniose visceral autóctone foi descrito no Município de Bom Sucesso, Minas Gerais, Brasil. O achado desse cão reagente à IFI levou a uma investigação epidemiológica nesse município. Essa investigação foi conduzida de março de 1999 a dezembro de 2005. Vinte e dois de um total de 734 (3 por cento) cães examinados foram reagentes à IFI. Entre os 22 cães IFI reagentes, seis apresentaram sintomas característicos de leishmaniose visceral canina. Os resultados desta investigação epidemiológica foram enviados às autoridades locais e estaduais de saúde pública requerendo medidas preventivas e de controle para leishmaniose visceral de forma a interromper a transmissão da doença e evitar a ocorrência de casos humanos.

Evaluation of enzyme-linked immunosorbent assay using crude Leishmania and recombinant antigens as a diagnostic marker for canine visceral leishmaniasis

The performances of ELISA assays with different antigen preparations, such as Leishmania amazonensis or L. chagasi lysates and the recombinant antigens rK-39 and rK-26, were compared using sera or eluates from dried blood collected on filter paper to detect anti-Leishmania antibodies in dogs from a visceral leishmaniasis-endemic area in Brazil. Of 115 IFAT-reactive dogs at 1:40 titre, 106 (92.2 percent) were positive in parasitological exams (skin and/or spleen). These animals were compared to healthy animals (n = 25), negative for IFAT at a titre of 1:40 and parasitological exams. The sensitivities of crude and recombinant antigens were similar and remarkably high for both sera and eluates (97-100 percent). Specificity was higher than 96 percent for sera and eluates for different antigens, except for L. chagasi antigen using eluates (88 percent). Concordance values among the tests were higher either for sera or eluates (J = 0.95-1.00). High concordances were observed between sera and eluates tested with different antigens (kappa = 0.93-0.97). Crude and recombinant antigens identified different clinical phases of canine leishmaniasis. These results show that eluates could be used in canine surveys to identify L. chagasi infection. Recombinant antigens added little when compared to crude antigen in identifying positive dogs. Cross-reactivity with other diseases whose distribution often overlaps VL-endemic areas is a limitation of crude antigen use however.