Comparative pathogenicity of single and mixed drug-resistant Trypanosoma brucei brucei and Trypanosoma congolense infections in rats

Drug-resistant trypanosomes are widespread in sub-Saharan Africa and in conjunction with the drug-sensitive phenotypes cause a serious endemic wasting disease in animals. We evaluated the pathogenicity of single and mixed drug-resistant Trypanosoma brucei brucei and T. congolense isolates in 35 female rats, randomly divided into seven groups (1–7) of five rats. Group 1 was the uninfected control. Groups 2 and 3 were infected with drug-sensitive T. brucei brucei and T. congolense, respectively, whereas groups 4 and 5 were infected with multidrug-resistant T. brucei brucei and T. congolense respectively. Group 6 were infected with drug-sensitive T. brucei brucei and T. congolense while group 7 were infected with multidrug-resistant T. brucei brucei and T. congolense. Parasitaemia kinetics, haematological parameters, body weight, clinical signs, survival time, gross and histopathological changes in the spleen were evaluated. Parasitaemia occurred between day 3–9 post-infection in all the infected groups. Rats in groups 4 and 7 had markedly prolonged (p