A serological study of Babesia caballi and Theileria equi in Thoroughbreds in Trinidad

Ninety-three (93) horses were investigated for serum antibodies to Theileria equi (T equi) and Babesia caballi (B. caballi) using the immunofluorescent antibody test (IFAT). Seventy-seven (82.8%) horses were seropositive; 31 (33.3%) were positive to T equi compared to 64 (68.8%) to B. caballi while 18 (19.4%) horses were seropositive to both parasites. No significant differences in antibody frequencies among females and males for either T equi or B. caballi were noted. Differences in scropositivity to B. caballi among age groups were not significant. Antibodies to T equi were more frequent than to B. caballi in the age group 5 years and over than in the 1-2 and 2-4 years age groups (p < 0.05). Unlike T equi antibodies, B. caballi antibodies in horses in the county of Caroni were significantly less frequent when compared to other counties (p < 0.05). Of 18 (19.4%) clinically ill horses, seven (42.9%) had clinicopathological evidence of anemia. Only one-third (6 of 18) horses were positive for the parasite on Wright-Giemsa stained blood smears and anemia was present in only 2. We report here that B. caballi and not T equi may be the more common agent of piroplasmosis in Trinidad. (c) 2006 Elsevier B.V. All rights reserved.