Abstract. We investigated the humoral immune response against different species of Rickettsia in serum samples from small rodents collected in two areas of a silent focus for Brazilian spotted fever in the eastern region of Minas Gerais State, Brazil. Sera samples were analyzed by indirect immunofluorescence assay using antigens from Rickettsia species of the spotted fever, ancestral, and transition groups. Titers 1:64 were considered positive. In Santa Cruz do Escalvado, 94% (30 of 32) of the samples collected from Rattus rattus, 22% (5 of 23) from Nectomys squamipes, and 80% (4 of 5) from Akodon sp., reacted by indirect immunofluorescence assay with Rickettsia antigens of the spotted fever group. In the municipality of Pingo D'Á gua, 84% (26 of 31) of the samples collected from R. rattus, 86% (6 of 7) of the samples from Oryzomys subflavus, 86% (6 of 7) from N. squamipes, and 100% (1 of 1) from Bolomys sp. contained antibodies that reacted with rickettsial antigens of the spotted fever group. These results demonstrated the previous exposure of small rodents to spotted fever group Rickettsia, suggesting the participation of these animals in the natural history of these rickettsiae in this region.
The main of the study was to evaluate the presence of Borrelia burgdorferi infection in domestic and wild vertebrates and ectoparasites in endemic areas from the state of Minas Gerais, Brazil. A total of 445 serum samples were examined by ELISA, which used the Borrelia burgdorferi strain G39/40 U.S. source and 3,821 tick samples were tested by polymerase chain reaction (PCR). B. burgdorferi antibodies were found in 30 serum samples (6.74%); three in marsupials (7.69%), three in rodents (2.80%), nine in dogs (6.25%), and 15 in horses (9.68%). Nested-PCR performed in DNA samples obtained from collected ticks demonstrated negative results. Although attempts to amplify B. burgdorferi DNA from ticks had been not successful, the presence of seroreactive vertebrates suggests the possibility the Borrelia species circulating in these regions. Further research is required to provide information on the presence of Borrelia in Brazilian territory and its association with Baggio-Yoshinari syndrome.
Introduction: The order Rickettsiales comprises a group of obligatory intracellular parasites, responsible for causing diseases known as rickettsial diseases. In Brazil, the most common rickettsial disease is the Brazilian spotted fever (FMB). Objectives: to determine the level of FMB endemicity in the city of Caratinga, Minas Gerais, in different epidemiological moments. Methods: epidemiological and serological surveys in residents from the most affected neighborhoods by the 1992 FMB outbreak and serological survey in domestic animals; in addition to serological survey in domestic animals and polymerase chain reaction in arthropod vectors collected in a new visit to the site in 2002. Results: in the first epidemiological survey carried out in 1992, 62.3% of the surveyed families reported contact with pastures. In the serological survey in humans, 2.1% of tested samples showed reactivity to Rickettsia rickettsii in the indirect immunofluorescence reaction (RIFI). In the serological survey on animals, conducted in 1993, 53.4% of equines and 25.0% of dogs were reactive for R. Rickettsii in RIFI. In a new visit to the site, over the period of 2002-2003, 13.4% of pools of DNA from examined arthropods and 17.0% of equine sera demonstrated positive results for R. rickettsii. Conclusions: the municipality of Caratinga can be considered, at the time, as a low transmission area remaining the recommendation to keep the epidemiological and acarological surveillance system active on the site and region.
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