Epidemiology of tick-borne diseases of cattle in Zimbabwe. II. Anaplasmosis.

A survey on the incidence of antibodies to Anaplasma marginale in one- to three-year-old cattle was carried out in Zimbabwe using the capillary tube agglutination test. Antibodies were detected in all but one of 118 batches of sera collected from different localities throughout the country. There was no clear relationship between the frequency of occurrence of positive serological reactors, which was similar in both commercial and communal farming areas, and the incidence of clinical anaplasmosis. However, the highest numbers of cattle exhibiting positive reactions were generally recorded from the areas that were most heavily tick infested. There was evidence that wild ungulates may serve as reservoirs of infection as antibodies to A. marginale were detected in sera from buffalo (Syncerus caffer) and impala (Aepyceros melampus).