Molecular detection and genetic analysis of Rickettsia, Ehrlichia, and Bartonella in ectoparasites from domestic dogs in Sinaloa, Mexico.

Tick- and flea-borne diseases, including rickettsiosis, bartonellosis, and ehrlichiosis, have increased in incidence globally in recent years, affecting both humans and animals. Although the circulation of these pathogens has been documented in Mexico, information from the state of Sinaloa remains limited. Despite environmental conditions that favor zoonotic transmission, the diversity of dog ectoparasites and the pathogens they harbor remains poorly studied. This study aimed to determine the frequency of the main ectoparasites infesting domestic dogs in Sinaloa, Mexico, and to molecularly and genetically identify Rickettsia, Ehrlichia, and Bartonella species harbored by these ectoparasites. Ectoparasites were collected from dogs in rural, urban, and suburban communities. A total of 2060 specimens were obtained from 306 dogs, with Rhipicephalus linnaei (86.74 %) and Ctenocephalides felis felis (10.45 %) being the most prevalent species. Other ticks, including Rhipicephalus microplus, Amblyomma inornatum, and Dermacentor variabilis; fleas (Ctenocephalides canis, Pulex irritans); and lice (Heterodoxus spiniger) were also identified. The molecular prevalence of Rickettsia spp. was 8.57 % in ticks and 13.63 % in fleas. Ehrlichia spp. was detected in 1.90 % of ticks, while Bartonella spp. was found in 9.09 % of fleas. Sequencing confirmed Rickettsia felis and Bartonella clarridgeiae in C. felis, and Rickettsia rhipicephali and Ehrlichia canis in R. linnaei. Factors associated with infestation included the dogs' living environment and frequency of outdoor activities. These results confirm the presence of Rickettsia, Ehrlichia, and Bartonella in ticks and fleas parasitizing domestic dogs in Sinaloa. The detection of these pathogens highlights a potential public health risk and underscores the need to enhance epidemiological surveillance in areas where ecological conditions favor the transmission of these understudied zoonoses.