Leishmania Seroprevalence in Dogs: Comparing Shelter and Domestic Communities

Canine leishmaniosis (CanL) is a chronic, systemic, and often severe disease. The main causative agent of CanL is a protozoan parasite, Leishmania infantum, with phlebotomine sand flies acting as vectors. In Europe and other continents, L. infantum is also responsible for leishmaniosis in other animals, such as cats, horses, and humans. In Portugal, animal and human leishmaniosis is endemic, and high prevalence levels of infections and disease have been reported in dogs. There is a prejudice against stray animals and also those housed in shelters, assuming they have higher levels of infection with vector-borne pathogens, including L. infantum, when compared to domestic animals. In northeastern Portugal, serum samples were obtained from March to May 2022 in three shelters (n = 179) and thirteen veterinary clinics (n = 164), resulting in 343 dogs being analyzed for antibodies to Leishmania spp. by the direct agglutination test (DAT). The overall seroprevalence was 9.9%, with 15.2% seroprevalence in domestic dogs and 5.0% in the shelter ones (p = 0.003). The fact that shelter dogs had a lower seroprevalence could be explained by more regular veterinary care provided in shelters regarding preventive measures, including insecticides with an antifeeding effect, in comparison with domestic dogs.