Diversity and Occurrence of Tick-Borne Pathogens in Small Ruminants and Their Ticks in Sardinia: Implications for...

Tick-borne diseases are an increasing concern in Mediterranean livestock systems, where environmental conditions and extensive grazing favour interactions among hosts, vectors, and pathogens. This study investigated the occurrence and diversity of tick-borne pathogens in small ruminants and their associated ticks in Sardinia (Italy), with the aim of characterizing the occurrence and diversity of tick-borne pathogens in small ruminants and their associated ticks in Sardinia. A cross-sectional survey was conducted on 17 farms in central-eastern Sardinia. Blood samples from 75 animals (57 goats and 18 sheep) and 364 ticks collected from infested hosts were analyzed. Ticks were morphologically identified, and both ticks and blood samples were screened for major bacterial and protozoan pathogens using rt-PCR and conventional PCR assays, followed by sequencing. Among examined hosts, Anaplasma spp. DNA was detected in 28% of goats and 39% of sheep, whereas Theileria ovis was identified in 4% of goats and 78% of sheep. No animals tested positive for Rickettsia spp. or Coxiella spp. Tick analysis revealed a predominance of Rhipicephalus sanguineus and Rhipicephalus bursa, with several tick-borne microorganisms detected, including Rickettsia spp. (26.6%), Coxiella spp. (22.5%), Anaplasma spp. (17.6%), and piroplasms (11.8%). Most Coxiella-positive ticks carried DNA of the Coxiella-like endosymbiont Candidatus Coxiella mudrowiae, while only one tick was positive for Coxiella burnetii. Sequencing confirmed the presence of zoonotic species such as Rickettsia massiliae, Rickettsia sibirica/barbarica group, and Rickettsia hoogstraalii. These findings reveal a complex epidemiological scenario characterized by frequent detection of tick-borne microorganisms in ticks but limited detection in hosts. The presence of zoonotic agents highlights potential public health risks and supports the need for integrated surveillance and control strategies in Mediterranean pastoral systems.