Cutaneous leishmaniasis (CL) is an infectious disease caused by various Leishmania species. It is among the most neglected tropical diseases and has been considered a major health threat over the past decades in the country. Its zoonotic form caused by Leishmania (L) major is the most prevalent in Morocco. This study investigated the population structure of L. major in southeastern Morocco. Samples (n = 67) were collected from patients with CL in five different endemic areas located in three provinces (Ouarzazate, Tinghir, and Zagora). These samples were then sequenced using two nuclear markers: internal transcribed spacer 1 (ITS1) and a fragment of the virulence factor GP63. Next, the sequences were edited and analyzed. Molecular diversity indices showed a high population genetic diversity but an overall low haplotype diversity. Our results suggest small population differentiation, indicating a low geographic structure. Tajima's D and Fu's Fs tests both suggested recent population expansion based on the significant deviations from neutrality in both tests for all populations except Tinghir, which may be due to a small sample size. Based on our findings, the region is experiencing rapid population expansion caused by recent CL outbreaks, and one of them has been recently studied. In addition, analysis of molecular variance and FST suggested gene flow between Zagora and both Ouarzazate and Tinghir. Nonetheless, no gene flow was observed between Tinghir and Ouarzazate. To the best of our knowledge, this is the first analysis of the population structure of L. major in Morocco. The results of this study provide crucial background information for epidemiological studies by showing the presence of gene flow between populations and clonal expansion in cases of an outbreak. This will drive authorities to reconsider the implemented control strategies.
Keywords: Gp63; Internal transcribed spacer 1; Leishmania major; Morocco; Population structure.
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