Molecular investigation of leishmaniasis in stray dogs in Southwest Iran: Confirmation of cutaneous and visceral species in blood samples.

Abstract

Leishmaniasis, with various clinical manifestations, is prevalent and remains a significant zoonosis and public health concern in Iran. Dogs are the main reservoir of cutaneous and visceral leishmaniasis. A cross-sectional study was conducted to assess leishmaniasis in blood samples from 87 stray dogs (55 without skin lesions and 32 with skin lesions) from shelters in Shiraz, southwest Iran, for the first time. Blood samples were collected from all dogs (with and without skin lesions) and skin lesions from dogs with dermatological lesions. To amplify the conserved region of the Leishmania kDNA minicircle, samples were subjected to a species-specific PCR assay. Skin lesion smears were also assessed by microscopic examination. The PCR amplicons were sequenced, assembled, and multiple-aligned with Leishmania strains retrieved from GenBank. Finally, the phylogenetic analysis was carried out. The results showed 8.05 % (7/87) leishmaniasis in all dogs (with and without skin lesions) and 21.87 % (7/32) in dogs with skin lesions. No Leishmania infection was detected in dogs without skin lesions by PCR. A significant association was found between skin lesions and leishmaniasis (P = 0.001). No significant association was found between sex and infection (P = 0.65). Phylogenetic analysis interestingly identified three species, including L. major, L. tropica, and L. infantum, with 95-98 % identities to documented sequences. Microscopic examination of skin smears confirmed the presence of amastigotes in 15.62 % (5/32) of the dogs with skin lesions. This study highlights the importance of sheltered stray dogs with skin lesions as potential reservoirs in dispersing zoonotic visceral and cutaneous Leishmania spp. in this region. It emphasizes the need for surveillance and control measures in shelters to prevent Leishmania transmission to the vectors, humans, and animal hosts. The study also elucidated that cutaneous parasites, identified more in skin lesions by circulating in dog blood, can be detected using kDNA PCR.