Differential virulence and tsetse fly transmissibility of Trypanosoma congolense and Trypanosoma brucei strains

• Published in: Onderstepoort journal of veterinary research Vol. 84; no. 1; pp. 1 - 10
• Main Authors: Murilla, Grace A., Wamwiri, Florence N., Ndung’u, Kariuki, Ngae, Geoffrey N., Thande, Paul C., Auma, Joanna E., Kurgat, Richard, Kibugu, James K., Thuita, John K., Gitonga, Purity K.
• Format: Journal Article
• Language: English
• Published: South Africa AOSIS 27-06-2017; African Online Scientific Information Systems (Pty) Ltd t/a AOSIS; AOSIS (Pty) Ltd; ARC-Onderstepoort Veterinary Institute - Agricultural Research Council
• Subjects: Africa; African trypanosomiasis; Agriculture, Dairy & Animal Science; Anatomy & Morphology; Anemia; Animals; Biochemistry & Molecular Biology; Blood meals; Chronic infection; Disease transmission; Health aspects; Immunology; Infections; Infectivity; Insect Vectors - parasitology; Laboratories; Livestock; Mice; Original Research; Parasites; Parasitology; Pharmacology & Pharmacy; Physiology; Protozoa; Standard error; Studies; Survival; Tropical diseases; Trypanosoma; Trypanosoma brucei; Trypanosoma brucei brucei - pathogenicity; Trypanosoma congolense; Trypanosoma congolense - pathogenicity; Trypanosome; Trypanosomiasis, African - epidemiology; Trypanosomiasis, African - parasitology; Trypanosomiasis, African - veterinary; Tsetse Flies - parasitology; Tsetse fly (Glossina palpalis); Vector-borne diseases; Veterinary medicine; Veterinary Sciences; Virulence; Virulence (Microbiology); virulence and tsetse infectivity; Virus-vector relationships
• ISSN: 0030-2465; 2219-0635; 2219-0635
• DOI: 10.4102/ojvr.v84i1.1412

African animal trypanosomiasis causes significant economic losses in sub-Saharan African countries because of livestock mortalities and reduced productivity. Trypanosomes, the causative agents, are transmitted by tsetse flies (Glossina spp.). In the current study, we compared and contrasted the virulence characteristics of five Trypanosoma congolense and Trypanosoma brucei isolates using groups of Swiss white mice (n = 6). We further determined the vectorial capacity of Glossina pallidipes, for each of the trypanosome isolates. Results showed that the overall pre-patent (PP) periods were 8.4 ± 0.9 (range, 4–11) and 4.5 ± 0.2 (range, 4–6) for T. congolense and T. brucei isolates, respectively ( p < 0.01). Despite the longer mean PP, T. congolense–infected mice exhibited a significantly ( p < 0.05) shorter survival time than T. brucei–infected mice, indicating greater virulence. Differences were also noted among the individual isolates with T. congolense KETRI 2909 causing the most acute infection of the entire group with a mean ± standard error survival time of 9 ± 2.1 days. Survival time of infected tsetse flies and the proportion with mature infections at 30 days post-exposure to the infective blood meals varied among isolates, with subacute infection–causing T. congolense EATRO 1829 and chronic infection–causing T. brucei EATRO 2267 isolates showing the highest mature infection rates of 38.5% and 23.1%, respectively. Therefore, our study provides further evidence of occurrence of differences in virulence and transmissibility of eastern African trypanosome strains and has identified two, T. congolense EATRO 1829 and T. brucei EATRO 2267, as suitable for tsetse infectivity and transmissibility experiments.