Leishmaniasis research by parasitological lymph node examination, PCR and species characterization by RFLP-PCR in municipal shelter dogs previously submitted to immunochromatographic testing

This study investigated Leishmania spp. infection in 153 dogs from a municipal shelter in an endemic area, previously tested as non-reactive by immunochromatography. Parasitological lymph node examination and PCR-RFLP directed to the chitinase gene were used for diagnosis and characterization of the species. The parasitological examination detected amastigotes in 3.3% of the dogs, while the PCR confirmed the infection in 1.3%, with high agreement between the methods (98%; Kappa=0.563; p<0.001). RFLP analysis identified the species as Leishmania infantum chagasi. The presence of clinical signs was not significantly associated with positive results. The results demonstrate the circulation of the parasite even in dogs with negative serological screening, evidencing the limitation of the isolated use of rapid tests and the need to adopt combined and more sensitive diagnostic protocols in shelters in endemic areas for the effective control of Canine Visceral Leishmaniasis.