Coexistence of Tick-Borne Pathogens in Ticks Collected from their Hosts in Sardinia: an Update.

Purpose: In recent decades, the incidence and distribution of tick-borne diseases have increased worldwide, attracting the attention of both clinicians and veterinarians. In Sardinia, notifiable tick-borne diseases are spreading and Mediterranean spotted fever (MSF) rickettsiosis continues to be endemic with an incidence of 10/10,000 inhabitants per year. Furthermore, ticks can transfer more than one pathogen after a single blood meal from a coinfected host or after multiple feeding on different infected hosts. The aim of this study was to update information on ticks and tick-borne diseases, focusing also on the presence of coinfection in Sardinian ticks.

Methods: The presence of protozoan (Theileria and Babesia species) and bacterial pathogens (Rickettsia spp., Anaplasma spp., Ehrlichia canis, Chlamydia spp., Bartonella spp., and Coxiella burnetii) was evaluated in 230 ticks collected from different hosts in Sardinia.

Results: PCR and sequencing analyses highlighted that the 59% of ticks were infected with at least one pathogen while the 15% resulted in coinfection by double and triple pathogens. Among the double co-infections, those of E. canis/C. burnetii, Babesia sp. Anglona/Ch. psittaci and Babesia sp. Anglona/C. burnetii revealed a statistically significant index of coinfection.

Conclusion: This study identifies new pathogens in Sardinian ticks and updates the information about tick-borne diseases in the island. We also provide new results on the presence of coinfections in collected ticks. The knowledge about the diversity of ticks and tick-borne diseases circulating in Sardinia is a necessary step toward implementing effective tick-borne disease prevention and control programs.