High prevalence of the Mediterranean spotted fever agent Rickettsia aeschlimannii in Hyalomma marginatum ticks from Pianosa island, Italy.

Tick-borne rickettsioses, caused by bacteria of the spotted fever group (SFG) Rickettsia, are emerging infectious diseases whose emergence and spread are often affected by climate and land-use changes. Here, we report the results of monitoring Hyalomma spp. ticks in the protected area of Pianosa island (Tuscany (Italy) and subsequently investigating their bacterial community through metabarcoding sequencing. In this study, based on analyses of 575 tick specimens distributed in 120 pools, we recorded a high prevalence of Rickettsia aeschlimannii (58% and 75% gltA- and 17 kDa-Ag protein-positive pools, respectively), an agent of the SFG group in H. marginatum. These findings support the need for warnings on the risk of transmission of spotted fever rickettsiosis to both residents and visitors and underline the need for enhanced surveillance, public awareness and preventive measures.