Dogs as rickettsiosis sentinels: Serological and molecular detection of Rickettsia spp. in blood and ectoparasites of dogs from Culiacán, Mexico
Abstract
Background: Rickettsioses are zoonotic diseases transmitted by ectoparasites, such as ticks and fleas, with increasing public health relevance in Mexico. Dogs act as hosts and epidemiological sentinels, reflecting the environmental circulation of Rickettsia spp. However, despite the favorable environmental conditions, information on the occurrence of Rickettsia spp. in dogs and their ectoparasites in Culiacán, Sinaloa, remains limited. Aim: To determine the serological and molecular presence of Rickettsia spp. in blood samples and ectoparasites collected from dogs in Culiacán’s urban and marginalized rural areas Methods: A cross-sectional descriptive study was conducted on 30 dogs selected through convenience sampling. Blood and ectoparasite (ticks and fleas) samples were collected. Serological detection of R. rickettsii and R. typhi was performed using an indirect immunofluorescence assay (IFA). Molecular detection was performed using polymerase chain reaction (PCR) targeting the ompB and 17-kDa genes. Results: A total of 356 ectoparasites were collected, with the tick Rhipicephalus linnaei (86.5%) and the flea Ctenocephalides felis (13.5%) being the only identified species. Seroreactivity to R. rickettsii was the most frequently observed (50.0%). Concurrent seroreactivity to both R. rickettsii and R. typhi was detected in 23.33% of the dogs, whereas exclusive reactivity to R. typhi and seronegative results each accounted for 13.33%. PCR results were positive in 40.0% of blood samples and 86.7% of ectoparasite samples. The spotted fever group rickettsiae were detected mainly in ticks, whereas the typhus group rickettsiae were detected in fleas. Conclusion: The findings suggest exposure to and circulation of Rickettsia spp. in dogs and their ectoparasites, with seroreactivity to R. rickettsii being the most frequently detected pattern. Dogs may serve as valuable epidemiological sentinels, underscoring the need for integrated surveillance, ectoparasite control, and timely diagnosis within the One Health framework