Molecular Tracking of Leishmania major in an Archived Rattus norvegicus Spleen Sample in Iran: A Case Report.

Rodents are the primary reservoir hosts for zoonotic cutaneous leishmaniasis (ZCL) caused by Leishmania major. Knowing reservoir hosts is crucial for leishmaniasis surveillance and control programs in endemic areas. In this study, we examined an archived spleen of Rattus norvegicus obtained during a pest control program in 2000 in Tehran, the capital of Iran. The sample was analyzed using polymerase chain reaction (PCR) and sequencing to determine the presence of Trypanosomatidae based on the internal transcribed spacer (ITS) 1 gene. Amplification and sequencing of the discriminative region of the ITS1 gene followed by BLAST analysis showed the highest similarity with L. major isolates. Also, the phylogenetic analysis revealed that our sample was grouped with L. major isolates retrieved from the GenBank database. This finding might support the claim that R. norvegicus acts as a potential reservoir host for L. major. Further studies, including a survey on more rodent samples as well as studying sandflies in the area, might uncover the possible presence of such pathobiological conditions in ZCL transmission in urban and suburban settings.