Pathogenicity of tsetse-transmitted Trypanosoma congolense for waterbuck (Kobus defassa) and Boran cattle (Bos indicus).

Five waterbuck (Kobus defassa) and four Boran cattle (Bos indicus) were infected with Trypanosoma congolense IL2895 using Glossina morsitans morsitans. At the same time, two waterbuck and two cattle were inoculated intravenously with bloodstream forms. With both methods of challenge, cattle had short prepatent periods followed by a continuous high parasitaemia. All cattle became severely anaemic and had to be treated with trypanocidal drugs to prevent death. In contrast, tsetse and intravenous challenge of waterbuck resulted in a long prepatent period, followed by brief, intermittent levels of low parasitaemia, and eventual selfcure. Waterbuck did not become anaemic, even during short bouts of parasitaemia which in general were very low. Both cattle and waterbuck developed parasite-specific antibodies, but some waterbuck failed to develop neutralizing antibodies. These results suggest that the ability of the waterbuck to resist trypanosome infection may not be mediated entirely by antibody-dependent immune processes.