Revisiting Leishmania (Viannia) lainsoni Silveira, Shaw, Braga, and Ishikawa, 1987: current knowledge and emerging perspectives.

More than three decades after its description, Leishmania (Viannia) lainsoni Silveira, Shaw, Braga, and Ishikawa, 1987 remains the least explored species of the subgenus Viannia Lainson and Shaw, 1987 within the genus Leishmania Ross, 1903. Although long considered rare and of limited clinical impact, recent records reveal a wider geographic range, diverse vector associations, and increasing involvement in American cutaneous leishmaniasis (ACL). Advances in molecular and genomic studies have clarified its taxonomy and uncovered notable biological and genetic variability. This review synthesizes current knowledge on the distribution, vectors, reservoirs, pathogenicity, and clinical relevance of L. (V.) lainsoni, highlighting emerging evidence that challenges earlier assumptions and emphasizing key research gaps for improving surveillance and understanding of its transmission dynamics.