Leishmania (Viannia) braziliensis in dogs in Brazil: epidemiology, co-infection, and clinical aspects

Leishmaniasis is an endemic disease present in 98 countries. In Brazil, the northeast region accounts for approximately half of the cases in humans, and has experienced an increased number of positive cases in dogs. In this study, we investigated the epidemiology of canine leishmaniasis in the city of Ilheus, Bahia, using serological and molecular techniques and evaluated the possible environmental risk factors and associated clinical signs. Blood samples were collected from 560 dogs in urban and peri-urban areas in Ilheus, northeastern Brazil. Genomic DNA was extracted from the selected animals and subjected to molecular analysis using Leishmania species-specific primers and diagnosis of Trypanosoma cruzi. A total of 54.72% of dogs were positive for Leishmania braziliensis, and animals positive for both Leishmania infantum and T. cruzi were not identified. Hematologic variables were not statistically associated with cases of L. braziliensis. However, the positive animal group showed lower red blood cell and platelet counts and higher levels of urea and serum creatinine. Few dogs presented clinical signs compatible with the presence of Leishmania. Age of more than 2 years and specific hair colors were associated with positive results for L. braziliensis. The geoclimatic characteristics of the region may improve parasite survival, reproduction, and vectors. This may explain the higher rate of dogs identified as positive in this study.