Investigations on the prevalence of trypanosome carriers and the antibody response in wildlife in Northern Botswana.

605 buffalo, 60 lechwe, 23 kudu, 23 impala, 15 tsessebe, 22 sable and two reedbuck from Northern Botswana were examined for trypanosome infections by serological and/or parasitological means. The indirect fluorescent antibody test (IFAT), the haematocrit centrifugation technique (HCT) and rodent subinoculation were used. The overall prevalence of patent infection with trypanosomes in buffalo, lechwe and reedbuck was 15,7%. In the case of buffalo and lechwe it was possible to classify their origin into high and low tsetse fly density areas. Serological and parasitological results showed a significantly higher prevalence of infections in areas with a high fly density. Buffalo showed a predominance of infections with Trypanosoma (Duttonella) vivax and T. (Nannomonas) congolense, while in lechwe infections with T. (Trypanozoon) brucei were as frequent. Strains of T. (T.) brucei isolated from buffalo, unlike those from lechwe, failed to infect rodents, 6 strains from lechwe proved sensitive to human serum (Blood Incubation Infectivity Test). Parasitological positive cases, antibody response and the age of buffalo were correlated. The number of patent infections in animals over one year rose to a peak at the age of 2 1/2 years and dropped steadily in the older buffalo. The frequency of positive antibody titres and their levels also increased after the first years of age, reached its peak at the age of four years an then persisted for the rest of the animals' life. Serological tests carried out on serum samples of the remaining species showed that kudu were more frequently infected than impala, tsessebe or sable.