Title : Potential for spread of Leishmania tropica in southern Europe by local sand flies
Various Leishmania species constitute an important global health problem with millions of people affected. Leishmania tropica is the causative agent of cutaneous leishmaniases (CL) in the Old World, occurring in many countries of Asia and Africa. Currently, a great concern is posed by outbreaks of CL in the Middle East, connected with people displaced from their homes due to civil war. In addition, imported cases of CL caused by L. tropica are increasingly documented in Europe among the general and migrant populations. The only proven vectors of Leishmania parasites are phlebotomine sand flies (Diptera: Phlebotominae). In most foci, L. tropica is transmitted by its specific vector Phlebotomus sergenti, a sand fly which is very rarely found in Europe. However, southern Europe is inhabited by other sand fly species and there is increasing evidence that they may also serve as vectors for L. tropica. We investigated the susceptibility of Phlebotomus perniciosus and Phlebotomus tobbi, two species widely distributed in the western and eastern parts of the Mediterranean basin, respectively, to infection with L. tropica. Laboratory-reared sand flies were infected experimentally with two L. tropica strains differing in geographical origin, epidemiology and surface molecules, particularly lipophosphoglycan epitopes. High infection rates, heavy parasite loads and fully developed late-stage infections, including colonization of the stomodeal valve, were observed in all parasite-vector combinations. In conclusion, we demonstrated that both sand fly species studied are susceptible to full development of various L. tropica strains which suggests that they may play a role in circulation of this parasite in southern Europe, the Middle East and northern Africa.