Spotted Fever Group Rickettsia in Small Rodents from Areas of Low Endemicity for Brazilian Spotted Fever in the Eastern Region of Minas Gerais State, Brazil

Abstract

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.

Serologic evidence of the exposure of small mammals to spotted-fever Rickettsia and Rickettsia bellii in Minas Gerais, Brazil

“…Reactivity was observed in BSF-endemic areas, in areas of silent focus, and also in apparently non-endemic areas [19,21,36]. In this regard, it was observed in the state of São Paulo, Brazil, in areas with or without a history of recent confirmed cases of human BSF, that rather than prevalence of opossum serum reactivity, the height of titers was related to endemicity [32].…”

“…However, due to the lack of antigens until a few years ago, there are only few reports on small mammal sera reactivity to several Rickettsia species in Brazil [6,19,21,32,36]. Unfortunately, these reports are not enough to establish a standard serological profile for circulation of Rickettsia species in small mammals.…”

Investigação sorológica de Rickettsia rickettsii e Coxiella burnetii em caprinos e ovinos no entorno do Parque Nacional da Serra das Confusões, Piauí

“…em 68,8% dos pequenos mamí-feros silvestres encontrados em áreas de Mata Atlântica, Pernambuco. Milagres et al (2013) verificaram soropositividade para R. rickettsii em 28,2% dos roedores silvestres capturados em Santa Cruz do Escalvado e em 23% dos roedores capturados em Pingo D' Água, Minas Gerais. Esses estudam possibilitam compreender o papel da fauna silvestre na circulação do agente etiológico e a possível transmissão para animais domésticos e humanos quando confirmada a presença do vetor.…”

Detecção de anticorpos anti-Rickettsia spp. em cães e equinos no estado de Mato Grosso, Brasil

“…No entanto, a circulação e manutenção das riquétsias dependem de hospedeiros amplificadores, como os gambás (Didelphis marsupialis) e as capivaras (Hydrochoerus hydrochaeris), que mantêm níveis altos de bacteremia por um período prolongado, permitindo que carrapatos não infectados adquiram a infecção (BURGDORFER, 1988;SOUZA et al, 2009). As infecções por riquétsias em capivaras (PACHECO et al, 2007), gambás (HORTA et al, 2007) e pequenos mamíferos não voadores (PENA et al, 2009;MILAGRES et al, 2013), também vêm sendo descritas por meio de análises sorológicas. Melo et al (2011) observaram pela RIFI uma prevalência de 47,5% de anticorpos anti-Rickettsia spp.…”