Detection of antibodies to the Ehrlichia ruminantium MAP1-B antigen in goat sera from three communal land areas of Zimbabwe by an indirect enzyme-linked immunosorbent assay.

A total of 1,286 caprine serum samples collected from three communal land areas in Zimbabwe from March 1999 to February 2000 were tested for Ehrlichia ruminantium antibodies using the indirect MAP1-B enzyme-linked immunosorbent assay. Of the 480 samples tested from Mudzi, a non-heartwater area, 425 (89.4 %) were positive. In the heartwater endemic areas, of the 441 samples 352 (79.4 %) from Gwanda and 300 of the 365 samples (83.2 %) from Bikita tested positive. The seroprevalence in the Bikita and Gwanda (approaching 90 %) is consistent with reports in related serological surveys that puts the seroprevalence of E. ruminantium in goats from endemic areas of Zimbabwe at 90 %. However, the high seroprevalence in the non-heartwater area of Mudzi is unexpected and can be a result of the presence of a serologically cross-reacting organism, which has to be isolated and characterized. The results need to be confirmed by alternative tests, based on molecular diagnostic tools. There were no significant differences in seroprevalence between the three sampling areas as there were between the three sampling periods. The highest corresponded with the period January to February (peak tick activity) and the lowest with the period July to September (minimal tick activity).