Authors

Discussion

Drug-resistant trypanosomes are widespread in the sub-Saharan Africa and in conjunction with the drug-sensitive phenotypes cause an important wasting and endemic protozoan disease in humans and animals. Using thirty-five female albino rats randomly divided into seven groups (1 – 7) of five rats each, pathogenicity of single and mixed drug-resistant Trypanosoma brucei and Trypanosoma congolense isolated from dogs was assessed. Group 1 served as the uninfected control group. Groups 2 and 3 rats were infected with 10⁶ drug-sensitive T. brucei and T. congolense respectively while groups 4 and 5 rats were infected with 10⁶ multidrug-resistant T. brucei and T. congolense respectively. Group 6 rats were infected with drug-sensitive T. brucei and T. congolense (5 × 10⁵ each)while group 7 rats were infected with multidrug-resistant T. brucei and T. congolense (5 × 10⁵ each). Pre-patent period (PPP), parasitaemic period, first peak parasitaemia, days to first peak parasitaemia (DTFPP), level of parasitaemia (LOP), clinical signs, body weight, rectal temperature, packed cell volume, haemoglobin concentration, red blood cell count, mean corpuscular volume, mean corpuscular haemoglobin, mean corpuscular haemoglobin concentration, total leucocyte count and survivability, gross and histopathological changes in the spleen were assessed. Parasitaemia occurred in all the infected groups between days 3 and 9 post infection. Groups 4 and 7 rats had longer (p<0.05) PPP, DTFPP, survivial time and lower (p<0.05) LOP than groups 2 and 6 rats while for groups 3 and 5 rats, these parameter were comparable. Anaemia was observed in the infected groups but the severity did not vary amongst the infected groups. Severe clinical signs and splenic lesions were observed in drug-sensitive trypanosome species infected groups of rats compared to the multidrug-resistant species. Therefore, we conclude that the trypanosome isolates were pathogenic. However, drug-sensitive T. brucei andmixed drug-sensitive T. brucei and T. congolense infections were more pathogenic than their multidrug-resistant counterparts.

Keywords: Drug-resistant trypanosomes; Trypanosoma brucei; Trypanosoma congolense; Pathogenicity; Clinical findings; Haematology; Rats.