Leishmania infantum (Trypanosomatida: Trypanosomatidae) detection in Nyssomyia neivai (Diptera: Psychodidae) and dogs in Southern Brazil

Background The sand fly Nyssomyia neivai is one of the most abundant species in Southern Brazil. It has been frequently found in visceral leishmaniasis foci in Santa Catarina (Brazil), a region where Lutzomyia longipalpis , the main vector of Leishmania infantum and the etiological agent of visceral leishmaniasis in the Americas, has not been identified. In the absence of the main Leishmania vector, this study aimed to identify the sand fly fauna and diagnose any potential Leishmania spp. infection in sand flies and dogs in a region with a recent canine visceral leishmaniasis outbreak in the South of Brazil. Methods We report here a sand fly fauna survey on the Zoonosis Control Center of Tubarão Municipality (Santa Catarina, Brazil). We also conducted molecular testing to detect Leishmania spp. natural infection on captured sand flies using polymerase chain reaction (PCR). In positive females, in addition to morphological identification, molecular analysis through DNA barcoding was performed to determine the sand fly species. Additionally, the dogs were tested for the presence of Leishmania spp. using a non-invasive technique for the collection of biological material, followed by PCR. Results We collected 3,419 specimens from five sand flies genera. Nyssomyia neivai (85.75%) was the most abundant species, followed by Migonemyia migonei (13.31%), Pintomyia fischeri (0.82%), Evandromyia edwardsi (0.03%), and the genus Brumptomyia spp. (0.09%). Leishmania infantum DNA was detected in two of the 509 analyzed females, yielding a natural infection rate of 0.4%. The L. infantum infected sand flies’ specimens were morphologically and molecularly identified as Ny. neivai . We analyzed 47 dogs’ conjunctival swabs for Leishmania spp. with two positive individuals for L. infantum (infection rate of 4.2%). Conclusions Our results confirm the presence of Ny. neivai naturally infected with L. infantum in an area where dogs were also infected by the parasite, suggesting its potential role as a vector in Southern Brazil. We emphasize the significance of DNA barcoding in supporting the sand flies’ identification, and the conjunctival swab technique proved effective in obtaining enough biological material for detecting L. infantum in dogs.