Horses infected by Piroplasms different from Babesia caballi and Theileria equi: species identification and risk factors analysis in Italy.

Equine Piroplasmosis (EP) caused by Theileria equi and Babesia caballi is a disease affecting the health and the international movement of horses. In order to assess prevalence of Piroplasmid infection in the Northwestern part of Italy and to evaluate the associated risk factors, whole blood was collected from 135 horses from 7 different stables across the study area. PCR and sequencing were used to assess prevalence of infection and to identify detected Piroplasms to species level. A total of 23 horses (P=17.04%; CI95%: 10.70-23.38%) was found to be infected with Piroplasms and T. equi was the most prevalent species, found in 18 animals (P=13.33%; CI95%: 7.60%-19.07%). Although B. caballi was never detected, the presence of parasites belonging to the genus Babesia was confirmed by sequencing in 5 horses, 3 of which were infected with B. canis (P=2.22%; CI95% 0.76%-6.33%), and 2 with B. capreoli (P=1.48%; CI95% 0.41%-5.24%). The natural reservoir hosts of B. canis and B. capreoli are the domestic dog and roe deer Capreolus capreolus respectively. These findings pose attention to the need of considering in future epidemiological and clinical studies, other Apicomplexan species as able to infect horses.