Abstract
Spotted fever group rickettsioses are emerging diseases. In some of these diseases, domestic dogs act as sentinels. Canine serological studies have demonstrated that rickettsial dispersion is concentrated in rural areas, seroprevalence being higher where human rickettsioses are endemic. In Rio de Janeiro, the Atlantic forest vegetation has been devastated by urbanization. In this context, we aimed to detect Rickettsia spp. in urban areas of the West Zone of Rio de Janeiro. Sera from 130 dogs were tested by Indirect Immunofluorescence Assay, and ticks collected from these dogs were tested by polymerase chain reaction. We found the rate of serological reactions against R. rickettsii and R. parkeri in our study area to exceed those of rural and non-endemic areas, highlighting the importance of dogs as urban sentinels. The possibility of contact with opossums and capybaras increased the chances of exposure to Rickettsia spp., reinforcing the hypothetical link between the landscape and the rickettsial wild cycle. Rhipicephalus sanguineus sensu lato was the tick most frequently observed. PCR-positive samples showed similarity with R. rickettsii and R. felis, an emerging pathogen rarely reported from ticks. We observed that rickettsiae circulate in urban places and ticks from indoor environments, which may be involved in bacterial epidemiology.
Highlights
Spotted fever group (SFG) rickettsioses are emerging and reemerging tick-borne zoonotic diseases (Fang et al., 2017)
Considering that SFG rickettsiae produce a strong cross-reaction outcome and that this study used two rickettsial antigens and tested dogs in a non-endemic area, our positive predictive value had a low score and did not allow us to elucidate the identification of the species involved
Rickettsial pathogens circulate in dogs from recently anthropized places inside the Rio de Janeiro city, and in ticks frequently found in indoor environments (R. sanguineus s. l.)
Summary
Spotted fever group (SFG) rickettsioses are emerging and reemerging tick-borne zoonotic diseases (Fang et al., 2017). Rickettsia rickettsii is known as the etiological agent of Brazilian Spotted Fever (BSF), a multi-systemic acute disease with a high lethality rate endemic to Brazil’s southeastern region (Oliveira et al, 2016). Dogs that live close to both humans and the ticks that act as vectors of BSF are useful sentinels of the disease (Cardoso et al, 2006; Cunha et al, 2014; Poubel et al, 2018). Serological studies in dogs show that rickettsial dispersions in Rio de Janeiro State are concentrated in rural areas of the southern or northwestern regions, where human BSF has been reported (Gazeta et al, 2009; Cunha et al, 2014; Poubel et al, 2018). Few studies have been conducted in other regions of Rio de Janeiro, especially the metropolitan area (Cordeiro et al, 2015)
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