A five-year survey of tick species and identification of tick-borne bacteria in Sardinia, Italy

Sardinia is a hotspot for studying tick-borne diseases in the Mediterranean region, where cases of notifiable tick-borne diseases are increasing. The aim of this study was to determine the presence of tick-borne bacteria of medical and veterinary importance in ixodid ticks collected from domestic and wild animals, humans, and vegetation from different collection sites in Sardinia. Using standard PCR and sequencing techniques, the presence of Rickettsia, Anaplasma, Ehrlichia, and Bartonella species, as well as Coxiella burnetii was evaluated. A total of 1619 ticks were morphologically identified as Rhipicephalus sanguineus sensu lato, R. bursa, R. annulatus, Dermacentor marginatus, Haemaphysalis punctata, Ha. sulcata, Hyalomma lusitanicum, H. marginatum, Ixodes festai (sometimes referred to erroneously as I. ventalloi), and Argas reflexus. Results indicated the presence of several circulating pathogens in Sardinian ticks. DNA of Rickettsia species was detected in 58 out of 1619 (4%) belonging to R. sanguineus s.l., D. marginatus, Ha. punctata, H. marginatum, and I. festai species. Ehrlichia canis DNA was detected in 33 out of 1619 ticks (2%) belonging to R. sanguineus s.l., R. bursa, and Ha. punctata species. A total of 61 out of 1619 (4%) ticks (R. sanguineus s. l., R. bursa, Ha. punctata, and I. festai) tested positive for Anaplasma spp. Coxiella burnetii was detected in 21 out of 1619 (1%) ticks belonging to R. sanguineus s.l., R. bursa, R. annulatus, and H. marginatum species. Five R. sanguineus s.l. and one R. bursa ticks were positive for the presence of Bartonella sp. 16S rRNA gene. Our findings expand the knowledge on tick-borne microorganism repertoires and tick distribution in Sardinia. Tick distribution should be monitored for effective control of these arthropods and the infections they transmit.