Anopheles sacharovi in Italy: first record of the historical malaria vector after over 50 years

Abstract

Abstract Anopheles sacharovi, a member of the Anopheles maculipennis complex, was a historical malaria vector in Italy, no longer found since the last report at the end of 1960s. In September 2022, within the Surveillance Project for the residual anofelism, a single specimen of Anopheles maculipennis sensu lato collected in Lecce municipality (Apulia region) was molecularly identified as Anopheles sacharovi. This record led to implement a targeted entomological survey in September 2023. Investigation was conducted in the areas around the first discovery, focusing on animal farms, riding stables and potential breeding sites. Adult and immature mosquitoes were collected, using active search or traps, in several natural and rural sites. Mosquitoes belonging to Anopheles maculipennis complex were identified morphologically and molecularly by a home-made routine qPCR assay, developed specifically for the rapid identification of Anopheles labranchiae, and, when necessary, by amplification and sequencing of the ITS-2 molecular marker. Out of the 11 sites investigated, 6 were positive for Anopheles presence. All 20 Anopheles maculipennis s.l. (7 adults, 10 larvae and 3 pupae) collected in the areas were identified as An. sacharovi by ITS-2 sequencing. The discovery of An. sacharovi, considered disappeared from Italy for over 50 years, has a strong health relevance and impact, highlighting an increase in the receptivity of the southern areas. As imported malaria cases in European countries are reported every year, the risk of Plasmodium introduction by gametocyte carriers among travellers from endemic countries should be given into greater consideration. Our findings allow rethinking and building new models for the prediction and expansion of introduced malaria and to further reconsider the need to strengthen the surveillance of residual anophelism throughout southern Italy in order to prevent the risk of reintroduction of the disease.