Serosurvey for Cowdria ruminantium, Coxiella burnetii, and spotted fever group rickettsiae in ostriches (Struthio camelus) from Zimbabwe

Sera from 216 ostriches on nine farms around Zimbabwe were examined by indirect fluorescent antibody (IFA) testing for the presence of antibodies reactive with Cowdria ruminantium, Coxiella burnetii, and Rickettsia africae, a spotted fever group rickettsia. Although no reactive antibodies could be detected to C. ruminantium or C. burnetii, 51/216 (35%) sera reacted with R. africae. The seroprevalence in ostriches from the south of Zimbabwe was significantly higher than in birds from the north (P < 0.01). Immunoblots of four sera positive by IFA (>1/160) showed antibodies reactive with antigens of R. africae that also were recognized by pooled sera from mice inoculated with the organism. No reactive antibodies could be detected in six sera negative by IFA.