author(s)
Anna F Ngumbi and Ladslaus Mnyone

abstract
The pathogenicity and transmissibility of T. congolense vary with its morphological appearance in the bloodstream. Similarly, we speculated that the morphological appearance of T. congolense varies with therapeutic sensitivity. Therefore, this study aimed to investigate whether the morphological appearance of drug-sensitive T. congolense-Mikese and drug-resistant T. congolense-Mbagala in host’s bloodstream vary from each other. Either T. congolense strains were inoculated into mice and cattle and monitored for morphological appearances and abundance in the bloodstream over time post-infection. In mice, the mean body length of drug-sensitive (12.38±1.66µm) and drug-resistant trypanosomes (12.58±2.03µm) was similar, except at day 6-8 post-infection. In cattle, the mean body length of drug-resistant trypanosomes (10.08±1.32µm) was significantly shorter than that of drug-sensitive trypanosomes (12.38±1.56µm). The categorization of observed trypanosomes based on their length demonstrated short-form intermediate-form and long-form. The abundance of short-form of bloodstream trypanosomes in both mice and cattle was significantly higher in drug-resistant than drug-sensitive T. congolense. In conclusion, these findings preliminarily suggest a correlation between the therapeutic sensitivity and morphological appearance of T. congolense. However, we recommend additional studies involving fine-scale measurements of other determinant morphological and/or behavioural features (kinetoplast, nucleus, organelle, flagella, pathogenicity and transmissibility).