A SURVEY OF THE INCIDENCE AND IMPORTANCE OF THE TICK-BORNE DISEASES HEARTWATER, REDWATER AND ANAPLASMOSIS IN THE HEARTWATER-ENDEMIC REGIONSOF SOUTH-AFRICA

In an almost 50 % response to a survey questionnaire, farmers in the h eartwater-endemic regions of South Africa indicated that they were exp eriencing losses of 1,3, 0,3 and 0,2 % in cattle due to heartwater, re dwater and anaplasmosis, respectively. In small stock, the heartwater mortality was 3,8 %. Only 35 % of cattle farmers and 15 % of farmers k eeping sheep and goats, vaccinate their animals against heartwater, It would seem that the present vaccine does not control heartwater adequ ately and, with 9% of farmers claiming poor protection after immunizat ion, it would be difficult to recommend wider use of the heartwater va ccine, Likewise, vaccination against redwater and anaplasmosis on 11,8 and 14,2 % of farms, respectively, appears to have had no beneficial effect on the mortality rates of these diseases. Many farmers still be lieve that very few or no ticks should be seen on cattle. In fact, it would appear that a considerable proportion of farmers find so few tic ks on their cattle, that the frequency of acaricidal treatment is in m any cases too high. Although there is no correlation between the incid ence of heartwater and the intensity of tick control, there is also no serological evidence to support the possibility of an endemically uns table condition. The concept that endemic stability as a means to cont rol heartwater in cattle can be achieved by allowing more ticks on ani mals, has not yet been established. The overall impression is that far mers do not regard heartwater in cattle as such a serious problem as i t is generally believed to be. In small stock, however, heartwater is a severe constraint in the bushveld regions of the Transvaal and in th e valley bushveld of the eastern Cape Province. In the latter, it is p articularly Angora goats that are affected.