Molecular detection of Theileria equi in donkeys (Equus asinus) in a selected site in central Italy

Equine piroplasmosis is among the most relevant tick-borne diseases of domestic and wild equids. Donkeys (Equus asinus) represent a potential reservoir for haemoparasites by harbouring tick-transmitted haemoparasites that can infect horses. We investigated the occurrence of Babesia caballi and Theileria equi in a donkey farm in the province of Grosseto (central Italy) to determine their prevalence of infection. For this purpose, conventional polymerase chain reaction (PCR) assays were carried out on blood samples from 109 donkeys. These included 85 females and 24 males as well as 36 young, 49 adult and 24 old animals. B. caballi and T. equi were detected by using primers that amplify an approximately 560 bp portion of the small-subunit ribosomal DNA of most Babesia and Theileria species. All PCR-positive samples were sequenced to determine the species of amplified Babesia and Theileria DNA. Sequencing data analysis revealed that 36 (33%, 95% CI: 24.2-40.9%) donkeys were positive for T. equi DNA. No samples were positive for B. caballi DNA. T. equi PCR-positivity drastically increased with age (from 0% to 46.9% and 54.2%) and was not significantly associated with the gender. These results highlight the high molecular prevalence of T. equi in a donkey farm of central Italy and support the role of donkeys as carriers and reservoirs of theileriosis for horses. The lack of B. caballi DNA needs further investigation.