Survey of rickettsiae in humans, dogs, horses, and ticks in Northern Paraná, Brazil

Brazilian Spotted Fever is a disease caused by Rickettsia rickettsii, and is transmitted to humans and animals by Amblyomma spp. The objective of this work was to study the epidemiology of spotted fever group rickettsiae in rural areas of Northern Parana. In Alvorada do Sul municipality, 88 humans, 83 dogs, and 18 horses were sampled, and in Arapongas municipality, 138 humans, 90 dogs and 18 horses were studied. All the sera were tested by IFA in which R. rickettsii and R. parkeri were used as antigens, considering titers ≥ 64 positive. Ticks collected from dogs and horses were tested by PCR. In Alvorada do Sul, 24% and 16.1% of humans, 55.6% and 22.2% of horses and, 22.9% and 18.1% of dogs were seropositive for R rickettsii and R. parkeri, respectively. In Arapongas, 9.4% and 4.3% of the humans, 5.6% and 5.6% of horses and, 13.3% and 12.2% of the dogs were seropositive for R. rickettsii and R. parkeri, respectively. PCR detected seven ticks with gltA sequences that showed similarity with R. bellii. The presence of antibodies to R. parkeri and R. rickettsii in dogs, horses and humans demonstrates a potential risk for spotted fever group rickettsiae in these areas.