A field study involving 309 horses was undertaken in the provinces of Arsi and Bale in the Ethiopian highlands to investigate the prevalence of Trypanosoma equiperdum
infections using
enzyme linked
immunosorbent assays (ELISAs) for the detection of both trypanosomal
antigen and antibody. Adult horses of both sexes were examined for clinical signs of T. equiperdum
infection and serum samples were collected for the assays. One hundred and one horses showed the presence of trypanosomal
antibodies in their serum and 70 animals showed typical clinical signs of
dourine. Nineteen horses showed the presence of trypanosomal
antigen. Eight horses were positive for both T. equiperdum antibody and
antigen. Blood and genital washes from seven antigenaemic horses were inoculated into mice and rabbits in an attempt to isolate trypanosomes but none became infected. Statistical analysis of the results of antibody assays indicated that there were significant differences in the distribution of serologically positive horses in the different clinical groupings, with seropositivity increasing with the severity of the observed clinical signs (P < 0.001). There was also a positive correlation between the presence of circulating trypanosomal
antigen and clinical evidence of
infection. Although it was not possible to obtain direct parasitological evidence of
infection, the results of the serological assays, together with the clinical signs of disease observed in many of the horses, provide strong circumstantial evidence that T. equiperdum occurs in Arsi and Bale provinces of Ethiopia. Furthermore, in view of the large number of horses in Ethiopia and the unrestricted movement of animals throughout the country it is likely that
dourine may be more widespread in Ethiopia than is currently realised. The assays used show potential for diagnosis of
dourine, but to be widely applied in field situations for the diagnosis and control of
dourine in Africa they require validation of their specificity and sensitivity.