A sero-epidemiological survey of equine piroplasmosis in the northern and eastern Cape Provinces of South Africa.

Serum samples from yearling Thoroughbred horses (n = 176) in the magisterial districts of Colesberg, Venterstad, and Wodehouse in the Northern and Eastern Cape Provinces were collected between September and November 1995 to determine the prevalence of antibodies to Babesia equi and Babesia caballi in these regions. Samples were examined for specific antibodies using the indirect fluorescent antibody test. The 95% confidence intervals for the prevalence of serum antibodies in the 3 districts combined varied from 47% to 61% for B. equi and from 26% to 40% for B. caballi. Antibody prevalence did not correlate with the known distributions of the tick vectors (Rhipicephalus evertsi evertsi and Hyalomma truncatum). Colts had a significantly higher prevalence of antibodies against B. caballi than fillies. No such difference could be determined for B. equi.