Epidemiological, clinical and molecular characterization of tegumentary leishmaniasis in the Emilia-Romagna region

Leishmaniasis is a parasitic disease caused by different Leishmania species and transmitted by phlebotomine sandflies. The disease is endemic in over 100 countries, including southern Europe. Clinical spectrum is determined by the parasite species and host characteristics, ranging from the severe visceral leishmaniasis (VL) to tegumentary leishmaniasis (TL), which includes cutaneous (CL), and mucosal (ML) forms. As in other Mediterranean areas, leishmaniasis is emerging in the Emilia-Romagna region (RER) (northeastern Italy) causing multiannual epidemic foci of VL and TL. Despite the strengthening of surveillance system, the prevalence of TL in RER is only partially known. The focus of the project was to collect and process epidemiological data and clinical samples to (1) better understand the TL burden and (2) characterize the Leishmania population causing TL in the RER with molecular tools. Study I analyzed 135 TL cases diagnosed in RER between 2017 and 2020; most cases (84%) were autochthonous and 8% were ML cases. The organization of a multicentric network of surveillance significantly contributed to recover unnotified cases and to gather important clinical and epidemiological data. In study II, we successfully typed 80% of the n=109 TL samples collected between 2014 and 2020 by combining two typing tools, internal transcribed spacer (ITS) 1 and heat shock protein (hsp)70. Sequencing results identified 8 imported and 75 autochthonous cases. Among the latter, we observed a high variability of the analyzed hsp70 conserved sequence, suggesting the presence of distinct Leishmania infantum populations causing TL in the RER. In study III, we used Oxford Nanopore Technologies NGS, to sequence the complete coding region of kinetoplast maxicircles from two TL isolates from northeastern Italy. The assembled sequences revealed a marked phylogenetic divergence between the two isolates and the other Southern-European L. infantum strains, confirming the presence of a peculiar dermotropic strain circulating in the area.