A sero-epidemiological survey of blood parasites in cattle in the north-eastern Free State, South Africa.

A survey to determine the incidence of parasites in cattle (n = 386) was conducted in the north eastern Free State between August 1999 and July 2000. Giemsa-stained blood smears were negative for blood parasites. A total of 94% of the cattle were sero-positive for Babesia bigemina by indirect fluorescent antibody test while 87% were sero-positive for Anaplasma by enzyme-linked immunosorbent assay. The observation of negative blood smears but high incidence of positive serological results for Anaplasma and Babesia for the same group of cattle indicates that this area is endemic for these diseases but with a stable disease situation. All the animals were sero-negative for B. bovis and this is probably because the tick vector (Boophilus microplus) which transmits the disease is not present in the Free State Province. Two tick species belonging to the family ixodidae were found on cattle, namely Boophilus decoloratus and Rhipicephalus evertsi evertsi. In the present study significant differences in seasonal burdens of B. decoloratus occurred, with the highest infestations recorded from February to June. The presence of R. evertsi evertsi throughout the year without any or with small fluctuations in winter months was observed, with a peak from February to May.