Canine visceral leishmaniasis in riverside communities of the Cuiaba river watershed

Visceral Leishmaniasis (VL) is a parasitic zoonosis expanding in Brazil. Several municipalities in the state of Mato Grosso including those on the river Cuiaba have reported the incidence of both human and canine cases and the identification of sandfly vector, Lutzomyia longipalpis and Lu. cruzi. Dogs are considered the main reservoir of Leishmania chagasi in the urban areas, hence, we devised a cross-sectional study aimed at assessing the prevalence of the infection in the dogs of riverside communities on Cuiaba River watershed by parasitological (parasitic isolation in culture), serological, and molecular methods. Of the 248 surveyed dogs, 24 were positive in enzyme linked immunosorbent assay (ELISA) or immunofluorescence antibody test (IFAT), with a prevalence of 9.7%. The riverside communities located in the town of Santo Antonio do Leverger displayed a higher prevalence of the disease than the cities of Cuiaba and Varzea Grande; however, the difference was not statistically significant (p > 0.05). Dogs born in the communities had a 3.24-fold higher risk of acquiring the infection. Promastigote were isolated in the axenic culture from the bone marrow samples and intact skin. Further, DNA of Leishmania sp. was detected in the bone marrow samples, lymph nodes, leukocyte cover, and skin of only one examined dog. These samples were sequenced and they showed 99% homology to L. infantum. To conclude, we observed a higher prevalence of infection in Riverside communities of Santo Antonio do Leverger and the confirmation of autochthony in these areas justifies the surveillance actions to minimise the risk of transmission within the riverine community itself, besides its dissemination to other areas by tourism.