RESUMEN

Ticks are vectors of various pathogens, including Rickettsia spp., which are responsible for causing an emerging disease of global significance. In the present study, an epidemiological survey was performed to identify Rickettsia spp. of the spotted fever group (SFG) in ticks and wild hosts in a native forest adjacent to livestock farming activity. The ticks and blood were evaluated by a hemolymph test and by PCR using the primers CS78 and CS323, which target a partial sequence of the enzyme citrate synthase (gltA) gene. Positive samples by PCR were further tested with the primers Rr190.70p and Rr190.602n, which target a 532-bp fragment of the rickettsial 190-kDa outer membrane protein gene (ompA). In addition, an indirect immunofluorescence assay (IFA) was performed to detect antibodies against Rickettsia spp. in horses that inhabited the same area. From the 43 animals that were captured, 192 ticks were collected; the ticks belonged to the species Amblyomma cajennense, A. ovale, and A. nodosum. All blood samples and hemolymph tests were negative. Four samples of A. nodosum that were collected from Tamandua tetradactyla were positive for Rickettsia spp. by PCR, and 8 samples of horse serum displayed titers greater than or equal to 1:64 by IFA. The phylogenetic analysis based on the DNA sequence of the ompACG gene demonstrated that Rickettsia spp. CG (the canadensis group) segregate in the same cluster as Rickettsia parkeri strain COOPERI, with a bootstrap value of 78%. These results indicate that Rickettsia spp. CG circulate among the tick population in the study area, which has a constant presence of livestock and humans. This may be the same species of Rickettsia that was recorded in A. nodosum throughout the Atlantic forest.

Asunto(s)

RESUMEN

There are data indicating that the distribution of Trypanosoma vivax in the Brazilian territory is expanding with potential to reach other areas, where the vectors are present. The detection of anti-trypanosomal antibodies in serum provides important information of the trypanosomal status in cattle herds. For this reason, an enzyme-linked immunosorbent assay (Tv-ELISA-Ab) with crude antigen from one Brazilian isolate of T. vivax was developed and evaluated. The sensitivity and specificity were respectively 97.6 and 96.9%. In the evaluation of cross-reactions, three calves inoculated with T. evansi trypimastigotes blood forms showed optical densities (OD) under the cut-off during the whole experimental period, except one at 45 days post-inoculation. With relation to Babesia bovis, B. bigemina, and Anaplasma marginale, which are endemic hemoparasites in the studied area, the cross-reactions were shown to be 5.7, 5.3, and 1.1%, respectively. The first serological survey of Pantanal and state of Pará showed that T. vivax is widespread, although regions within both areas had significantly different prevalences. Therefore, this Tv-ELISA-Ab may be a more appropriate test for epidemiological studies in developing countries because the diagnostic laboratories in most countries may be able to perform an ELISA, which is not true for polymerase chain reaction.

Asunto(s)

RESUMEN

O diagnóstico presuntivo da tuberculose bovina é baseado na análise da resposta imune celular a antígenos micobacterianos. Procedeu-se à simulação experimental de sensibilização por Mycobacterium bovis e Mycobacterium avium inativados em bovinos a fim de acompanhar a resposta imune a partir do teste cervical comparativo e da evolução da produção específica de interferon-gama, além de identificar a interferência de reações inespecíficas por M. avium nos resultados dos testes. Verificou-se que os animais desencadearam resposta de hipersensibilidade tardia contra os bacilos inativados, e que ambos os testes diagnósticos da tuberculose bovina foram eficientes na identificação dos animais sensibilizados com M. bovis e na discriminação das reações geradas pela inoculação dos bovinos com M. avium.

The presumptive diagnosis of bovine tuberculosis is based on analysis of the immune response to micobacterial antigens. This experimental simulation of sensibilization by Mycobacterium bovis and Mycobacterium avium in cattle aimed to verify the immune response by both the cervical comparative test and the evolution of the specific production of gamma-interferon, and also to identify interference of unspecified reactions by M. avium on the test results. The results support that the experimental animals started a response of delayed hypersensitivity to the inactivated bacilli, and that both diagnostic tests for bovine tuberculosis were efficient for the identification of animals sensitized with M. bovis and for discrimination of reactions generated by inoculation of cattle with M. avium.

Asunto(s)

RESUMEN

There are data indicating that the distribution of Trypanosoma vivax in the Brazilian territory is expanding with potential to reach other areas, where the vectors are present. The detection of anti-trypanosomal antibodies in serum provides important information of the trypanosomal status in cattle herds. For this reason, an enzyme-linked immunosorbent assay (Tv-ELISA-Ab) with crude antigen from one Brazilian isolate of T. vivax was developed and evaluated. The sensitivity and specificity were respectively 97.6 and 96.9 percent. In the evaluation of cross-reactions, three calves inoculated with T. evansi trypimastigotes blood forms showed optical densities (OD) under the cut-off during the whole experimental period, except one at 45 days post-inoculation. With relation to Babesia bovis, B. bigemina, and Anaplasma marginale, which are endemic hemoparasites in the studied area, the cross-reactions were shown to be 5.7, 5.3, and 1.1 percent, respectively. The first serological survey of Pantanal and state of Pará showed that T. vivax is widespread, although regions within both areas had significantly different prevalences. Therefore, this Tv-ELISA-Ab may be a more appropriate test for epidemiological studies in developing countries because the diagnostic laboratories in most countries may be able to perform an ELISA, which is not true for polymerase chain reaction.

Asunto(s)

RESUMEN

O diagnóstico presuntivo da tuberculose bovina é baseado na análise da resposta imune celular a antígenos micobacterianos. Procedeu-se à simulação experimental de sensibilização por Mycobacterium bovis e Mycobacterium avium inativados em bovinos a fim de acompanhar a resposta imune a partir do teste cervical comparativo e da evolução da produção específica de interferon-gama, além de identificar a interferência de reações inespecíficas por M. avium nos resultados dos testes. Verificou-se que os animais desencadearam resposta de hipersensibilidade tardia contra os bacilos inativados, e que ambos os testes diagnósticos da tuberculose bovina foram eficientes na identificação dos animais sensibilizados com M. bovis e na discriminação das reações geradas pela inoculação dos bovinos com M. avium. (AU)

The presumptive diagnosis of bovine tuberculosis is based on analysis of the immune response to micobacterial antigens. This experimental simulation of sensibilization by Mycobacterium bovis and Mycobacterium avium in cattle aimed to verify the immune response by both the cervical comparative test and the evolution of the specific production of gamma-interferon, and also to identify interference of unspecified reactions by M. avium on the test results. The results support that the experimental animals started a response of delayed hypersensitivity to the inactivated bacilli, and that both diagnostic tests for bovine tuberculosis were efficient for the identification of animals sensitized with M. bovis and for discrimination of reactions generated by inoculation of cattle with M. avium. (AU)

Asunto(s)