Date Published: December 8, 2015
Publisher: Public Library of Science
Author(s): Dhekra Chaara, Anne- Laure Bañuls, Najoua Haouas, Loïc Talignani, Patrick Lami, Habib Mezhoud, Zoubir Harrat, Jean-Pierre Dedet, Hamouda Babba, Francine Pratlong, Alain Debrabant. http://doi.org/10.1371/journal.pntd.0004204
Abstract: Leishmania (L.) killicki (syn. L. tropica), which causes cutaneous leishmaniasis in Maghreb, was recently described in this region and identified as a subpopulation of L. tropica. The present genetic analysis was conducted to explore the spatio-temporal distribution of L. killicki (syn. L. tropica) and its transmission dynamics. To better understand the evolution of this parasite, its population structure was then compared with that of L. tropica populations from Morocco. In total 198 samples including 85 L. killicki (syn. L. tropica) (from Tunisia, Algeria and Libya) and 113 L. tropica specimens (all from Morocco) were tested. Theses samples were composed of 168 Leishmania strains isolated from human skin lesions, 27 DNA samples from human skin lesion biopsies, two DNA samples from Ctenodactylus gundi bone marrow and one DNA sample from a Phlebotomus sergenti female. The sample was analyzed by using MultiLocus Enzyme Electrophoresis (MLEE) and MultiLocus Microsatellite Typing (MLMT) approaches. Analysis of the MLMT data support the hypothesis that L. killicki (syn. L. tropica) belongs to the L. tropica complex, despite its strong genetic differentiation, and that it emerged from this taxon by a founder effect. Moreover, it revealed a strong structuring in L. killicki (syn. L. tropica) between Tunisia and Algeria and within the different Tunisian regions, suggesting low dispersion of L. killicki (syn. L. tropica) in space and time. Comparison of the L. tropica (exclusively from Morocco) and L. killicki (syn. L. tropica) population structures revealed distinct genetic organizations, reflecting different epidemiological cycles.
Partial Text: Leishmaniases are vector-borne diseases caused by several Leishmania species that cycle between their phlebotomine sandfly vectors and mammalian reservoir hosts . Leishmania parasites, like many other microorganisms, have a high adaptation capacity that allows them to invade and survive in various ecosystems. The spread of a parasitic genotype or group of genotypes in new ecosystems can lead to population differentiation. Consequently, new Leishmania taxa have regularly been described during the last decades [2–4]. Leishmania killicki could be considered as a typical example of this evolutionary process. Rioux et al.  identified this parasite in the Tataouine province (South Eastern Tunisia) for the first time in 1980. Then, sporadic cases were reported in Kairouan and Sidi Bouzid (Center of Tunisia), Gafsa (South Western Tunisia) and Séliana (Northern Tunisia) [6–8]. Besides Tunisia, this taxon was described in Libya  and Algeria [10–12]. The probable zoonotic transmission of this parasite, with the Ctenodactylus gundi rodent as reservoir and Phlebotomus (P.) sergenti as vector, was suggested but needs to be confirmed [13–17].
In the “Materials and Methods” and “Results” sections, L. killicki has been used at the place of L. killicki (syn. L. tropica) for easy reading.
Despite a great knowledge on Leishmania parasites, many taxa, such as L. killicki (syn. L. tropica), are still not completely characterized. The main objective of this study was to understand the epidemiology and transmission dynamics of L. killicki (syn. L. tropica) by analyzing its population structure and by comparing the genetic patterns of L. killicki (syn. L. tropica) and L. tropica populations in Maghreb.