Canine vector-borne pathogens in rural dogs in Chile: molecular survey and co-infection patterns

Abstract

Background: Canine vector-borne pathogens (CVBP) comprise a relevant and globally distributed group of disease agents. The aim of this study is to determine de co-occurrence of the most relevant CVBP of veterinary and zoonotic interest, in free-ranging, owned, rural dogs of central Chile, and to evaluate risk factors and potential non-apparent hematological alterations associated to pathogen co-infection by two or more agents.Methods: Nine groups of canine vector-borne pathogens (CVBP) were molecularly investigated in 111 free-ranging, owned rural dogs in the Metropolitan Region of Chile. Results: At least one pathogen was detected in 75% of the dogs. The most prevalent agent was Anaplasma platys (36%), followed by Candidatus Mycoplasma haematoparvum (CMhp; 31%), Mycoplasma haemocanis (Mhc; 28%), Trypanosoma cruzi (17%), Leishmania spp. (4.5%) and Acanthocheilonema reconditum (1%). DNA of Ehrlichia spp., Rickettsia spp., Bartonella spp., Piroplasmida and Hepatozoon spp. was not detected. Thirty-eight dogs (34%) were coinfected, either by two (n=20), three (n=7), or four agents (n=1). The most common co-infection pattern was CMhp – Mhc (n=14). CMhp was involved in 71%, Mhc in 58%, and A. platys in 50% of the co-infections. Prevalence of A. platys was higher in juvenile than in adult dogs, whereas the opposite was found for CMhp and Mhc. Adult dogs had five times more probabilities of being coinfected than young animals. Dogs positive for A. platys were infested by a larger number of Rhipicephalus sanguineus sensu lato ticks than uninfected individuals. At clinical evaluation, most of the animals were considered healthy, with only eight dogs (7%) presenting pale mucous membranes. Co-infected animals showed higher white blood cell count, segmented neutrophil count and GGT levels than non-co-infected dogs. Conclusions: Widespread occurrence of and co-infection by CVBP was found in rural free-ranging dogs of central Chile. This study represents the first report of Leishmania spp. in Chile. Clinically healthy but infected dogs as those studied here may act as reservoirs of CVBP, potentially contributing to the spread of these pathogens to other tick-exposed dogs as well as human beings or wild carnivores.