Genetic Profiling of Leishmania Species Causing Human Visceral Leishmaniasis in Algeria.

BACKGROUND: Human visceral leishmaniasis (HVL) in Algeria is primarily caused by Leishmania infantum. This study aimed to genetically identify the Leishmania species responsible for HVL in Algerian patients. METHODS: This descriptive molecular case series included 13 patients diagnosed between 2010 and 2022. DNA from blood, bone marrow, and skin lesion smears was analyzed using ITS1-PCR, RFLP analysis and Sanger sequencing. The resulting sequences were compared with GenBank references, and phylogenetic analyses were performed. RESULTS: L. infantum was identified in 11 of 13 cases (84.6%). Most visceral leishmaniasis cases occurred in patients younger than 16 years, whereas adult cases were primarily immunocompromised patients, particularly those living with HIV/AIDS. Phylogenetic analyses revealed a high degree of similarity between Algerian L. infantum isolates and Mediterranean strains. In addition to L. infantum, L. tropica DNA and, surprisingly, L. major DNA was also identified. L. major DNA was detected in one immunocompetent child, while L. tropica DNA was detected in a skin lesion of an immunocompromised adult who presented with a concomitant relapse of HVL. These atypical molecular findings require cautious interpretation and further investigation. CONCLUSIONS: L. infantum remains the principal causative agent of HVL in Algeria. The atypical molecular findings should be interpreted cautiously and highlight the need for continued molecular surveillance, larger studies incorporating additional genetic markers, and investigations of vector dynamics and animal reservoirs.