Blood parasites of some wild bovidae in Botswana.

Blood smears from a total of 282 wild Bovidae from Ngamiland, Botswana were examined for the presence of blood parasites. The following species were sampled: 190 African buffalo, 23 impala, 10 blue wildebeest, 18 tsessebe, 1 eland, 13 lechwe, 16 kudu and 11 sable antelope. In addition, blood from 36 of the above antelope and from a further 48 buffalo was inoculated into rodents to test for the presence of trypanosomes. An anaplasm morphologically indistinguishable from Anaplasma marginale Theiler, 1910 was found in 28,4% of buffalo. The incidence of detectable cases of A. marginale infection in buffalo less than 5 years of age was significantly higher than in those 5-10 years of age (P less than 0,02). Furthermore, the level of parasitaemia was higher in young than in old buffalo. Theilerail piroplasms were found in all 8 species and were detected in 16,3% of buffalo. Two morphological types were found in impala; clinical cytauxzoonosis was suspected in 1 impala. A large Babesia occurred in the erythrocytes of 1 blue wildebeest. Erythrocytic discrasia, associated with the presence of a small Babesia was found in 1 tsessebe. Trypanosoma (Nannomonas) congolense was found in blood smears from 4 buffalo, 1 impala, 1 lechwe and 1 kudu and T. (Trypanozoon) brucei occurred in smears from 2 buffalo and 1 kudu, but all 84 rodent inoculations were negative. The overall incidence of trypanosome infections detected was 2,5% in buffalo and 4,3% in the other species. Protozoa resembling the cyst organisms of Sarcocystis spp., probably originating from cysts ruptured accidentally, occurred in the blood films of 2 impala and 1 tsessebe. The parasite Haematoxenus was not detected in any of the blood smears. The findings are compared with those of workers in other African countries and the importance of blood parasites in wild animals is discussed.