Viscerotropic Leishmaniasis in Iran: Current Insights and Future Directions: A Narrative Review

This narrative review synthesizes the current evidence on the geographic distribution, diagnostic approaches, and clinical and epidemiological characteristics of Viscerotropic leishmaniasis (VTL) in both human and animal hosts in Iran. A comprehensive search of electronic databases (PubMed, Web of Science, etc.) was conducted for articles (1997 to 2025) reporting VTL in Iran with PCR-based species confirmation. Twenty-three studies met the inclusion criteria and were analyzed. The findings indicate that VTL in Iran is predominantly caused by Leishmania tropica, with notable cases attributed to L. major. A key finding is the frequent reporting of treatment failure with pentavalent antimonials in these VTL cases. Conversely, L. infantum, the typical agent of visceral leishmaniasis (VL), has also been implicated in CL across various regions, suggesting its potential role in dermotropic leishmaniasis (DL) in humans. Rare cases of L. tropica-induced VTL in dogs highlight a potential zoonotic dimension. Reported treatment failure with first-line antimonials in several VTL cases caused by these species, highlighting a critical therapeutic challenge. VTL, primarily caused by L. tropica, represents an emerging public health concern in Iran with distinct epidemiological and therapeutic implications. The reviewed evidence underscores an urgent need for rapid diagnostic tools to differentiate VTL from classic VL and to guide species-specific treatment, as standard antimonial therapy often fails. A multidisciplinary approach integrating enhanced surveillance, targeted research, and revised clinical guidelines is essential to mitigate the burden of this neglected disease.