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. 2017 Jun 27;84(1):e1-e10.
doi: 10.4102/ojvr.v84i1.1412.

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

Purity K Gitonga, Kariuki Ndung'u  1 , Grace A Murilla, Paul C Thande, Florence N Wamwiri, Joanna E Auma, Geoffrey N Ngae, James K Kibugu, Richard Kurgat, John K Thuita
Affiliations

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

Purity K Gitonga et al. Onderstepoort J Vet Res. .

Abstract

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.

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Conflict of interest statement

The authors declare that they have no financial or personal relationships that may have inappropriately influenced them in writing this article.

Figures

FIGURE 1
FIGURE 1
Parasitaemia patterns in mice infected with (a) Trypanosoma congolense isolates and (b) Trypanosoma brucei isolates.
FIGURE 2
FIGURE 2
Mean packed cell volume profiles of mice (a) (n = 5) infected with isolates of Trypanosoma congolense savannah and (b) (n = 6) infected with various isolates of Trypanosoma brucei.
FIGURE 3
FIGURE 3
Bodyweight profiles of mice (a) (mean ± standard error of the mean; n = 4) infected with various isolates of Trypanosoma congolense and (b) (mean ± standard error of the mean; n = 5) infected with various isolates of Trypanosoma brucei.
FIGURE 4
FIGURE 4
Survival distribution functions of mice infected with various (a) Trypanosoma congolense isolates, (b) Trypanosoma brucei isolates and (c) Trypanosoma brucei and Trypanosoma congolense trypanosome isolates.
FIGURE 1-A1
FIGURE 1-A1
Comparison of mean ± standard error parasitaemia profiles in mice infected with Trypanosoma brucei and Trypanosoma congolense isolates.
See this image and copyright information in PMC

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