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Comparative pathogenicity of three genetically distinct Trypanosoma congolense-types in inbred Balb/c mice
1CIRDES-Centre International de Recherche-Developpement sur l'Elevage en Zone subhumide, 01BP 454, Bobo-Dioulasso, Burkina Faso. toure@ouaga.ird.bf
Abstract:
Inbred Balb/c mice were infected with three clones of Trypanosoma congolense (Sam.28.1, Dind.3.1 and K60.1A) corresponding, respectively, to the three genetically distinct types (savannah, forest and kilifi) defined within this species, for the purpose of comparing their pathogenicity for a better understanding of the epidemiology of African trypanosomosis. Another clone of savannah type, IL 3000, was also tested simultaneously to study a probable strain variation. Both the clones of savannah type were found of extreme virulence with loss of appetite, rough hair, rapid respiration, lethargy, and all mice died within a week. Parasitaemias evolved rapidly to the first peak by day 3-5 post-inoculation without any remission and the course of disease was correlated positively with the prepatent period. The clones of the forest type and the kilifi type were of low virulence with chronic infection and symptoms progressively less patent throughout the infection; only one mouse died in each experimental group.
Insights
African trypanosomosis pathogenicity varies by Trypanosoma congolense type. Savannah types are highly virulent, causing rapid death in mice, while forest and kilifi types exhibit low virulence and chronic infections.
Area of Science:
- Veterinary Parasitology
- Molecular Epidemiology
- Disease Pathogenesis
Background:
- African trypanosomosis is a significant disease affecting livestock and humans.
- Trypanosoma congolense exists in genetically distinct types, influencing disease presentation.
- Understanding type-specific pathogenicity is crucial for epidemiological control.
Purpose of the Study:
- To compare the pathogenicity of different Trypanosoma congolense types in mice.
- To investigate potential strain variations within the savannah type.
- To enhance the understanding of African trypanosomosis epidemiology.
Main Methods:
- Infection of inbred Balb/c mice with distinct Trypanosoma congolense clones (savannah, forest, kilifi).
- Inclusion of an additional savannah clone (IL 3000) to assess strain variation.
- Monitoring of clinical signs, parasitaemia, prepatent period, and mortality rates.
Main Results:
- Savannah type clones (Sam.28.1, IL 3000) demonstrated extreme virulence, leading to rapid mortality within a week.
- Forest (Dind.3.1) and kilifi (K60.1A) type clones exhibited low virulence, resulting in chronic infections and minimal mortality.
- Rapidly evolving parasitaemia in virulent infections correlated positively with the prepatent period.
Conclusions:
- Trypanosoma congolense type significantly influences pathogenicity and disease course in mice.
- Savannah type strains are highly virulent, posing a greater immediate threat.
- Forest and kilifi types cause chronic, less severe infections, impacting long-term disease dynamics.