Species-specific variation in predicted distribution and habitat suitability of phlebotomine sand flies in Italy under different climate change scenarios

The incidence of human and canine leishmaniasis in Europe is increasing and is a key indicator in the Lancet Countdown report on health and climate change 2024. While the potential distribution of the disease on a continental scale has been assessed under climate change scenarios, local analyses of vector species distribution are crucial for effective prevention strategies. Italy is endemic for Leishmania infantum, and expansions in the latitudinal and altitudinal distribution of canine cases and vector species have been recorded. This study evaluated the potential distribution of six phlebotomine sand fly species, known or suspected vectors of L. infantum, under climate change scenarios using ecological niche modeling and the maximum entropy (MaxEnt v. 3.4.1) modeling algorithm. We analyzed 410 records from 1979 to 2013 and projected future distributions for 2041-2060 and 2061-2080 using five CMIP5 models and two representative concentration pathways. Historical data from 1968 to 1972 were also examined to confirm suitable areas. The predictions indicate suitable habitats for sand flies throughout Italy, and variations among the different scenarios evaluated. All species show potential for expansion, such as the main vector, P. perniciosus, which shows an increase in the percentage of suitable habitat over time. On the other hand, predictions for P. perfiliewi don't show a clear pattern, with an initial decrease and subsequent increase in suitable areas. Shifts in the distribution of insect vectors may affect the dynamics of Leishmania transmission, highlighting the need for improved surveillance strategies.