Emerging Risk of Visceral Leishmaniasis in a Non-Endemic Area of Southern Brazil: Sand Fly Survey and Identification of a Dog Positive for Leishmania infantum Using a kDNA-Based PCR Assay.

In the state of Santa Catarina (SC), Brazil, the first autochthonous case of canine visceral leishmaniasis (CVL) was reported in Florianópolis in 2010, which remains the only municipality with confirmed human and canine cases. The primary vector of Leishmania infantum, Lutzomyia longipalpis, has not yet been detected in SC, and data on sand fly fauna and CVL are scarce. This study employed a three-pronged approach in the non-endemic municipality of Biguaçu, adjacent to Florianópolis: (i) development of a PCR assay targeting the kDNA minicircle of the Leishmania donovani complex for detection of L. infantum; (ii) collection and taxonomic identification of sand flies, followed by PCR-based screening for L. infantum DNA; and (iii) canine monitoring for L. infantum through non-invasive conjunctival swab sampling. The PCR assay proved specific for L. infantum and sensitive to 100 fg of DNA. Over 12 months, 367 sand flies were collected using CDC light traps at three sampling sites, revealing nine species. Three species with potential vector capacity were identified: Migonemyia migonei, Nyssomyia neivai, and Pintomyia fischeri. Psychodopygus geniculatus was recorded for the first time in Santa Catarina. No female sand fly tested positive for L. infantum. This constitutes the first description of the sand fly fauna in Biguaçu. Among 235 sampled dogs, one dog was PCR-positive for L. infantum, with infection confirmed by DNA sequencing. These findings suggest favorable conditions for the emergence of visceral leishmaniasis in Biguaçu, emphasizing the need to strengthen epidemiological surveillance and implement vector and reservoir control measures.