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Open Access Research

Identification of different trypanosome species in the mid-guts of tsetse flies of the Malanga (Kimpese) sleeping sickness focus of the Democratic Republic of Congo

Gustave Simo1*, Barberine Silatsa1, Njiokou Flobert2, Pascal Lutumba3, Philemon Mansinsa4, Joule Madinga3, Emile Manzambi5, Reginald De Deken6 and Tazoacha Asonganyi7

Author Affiliations

1 Department of Biochemistry, Faculty of Science, University of Dschang, PO Box 67, Dschang, Cameroon

2 Faculty of Science, University of Yaoundé 1, Yaoundé , Cameroon

3 Department of Tropical Medicine, School of Medicine, Kinshasa University, Kinshasa, Democratic Republic of Congo

4 Programme National de Lutte contre la Trypanosomiase Humaine Africaine, Kinshasa, Democratic Republic of the Congo

5 Institut National de Recherche Biomédicale, Kinshasa, Democratic Republic of the Congo

6 Department of Animal Health, Institute of Tropical Medicine, Nationalestraat 155, 2000, Antwerp, Belgium

7 Faculty of Medicine and Biomedical Sciences, University of Yaoundé 1, Yaounde, Cameroon

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Parasites & Vectors 2012, 5:201  doi:10.1186/1756-3305-5-201

Published: 19 September 2012

Abstract

Background

The Malanga sleeping sickness focus of the Democratic Republic of Congo has shown an epidemic evolution of disease during the last century. However, following case detection and treatment, the prevalence of the disease decreased considerably. No active survey has been undertaken in this focus for a couple of years. To understand the current epidemiological status of sleeping sickness as well as the animal African trypanosomiasis in the Malanga focus, we undertook the identification of tsetse blood meals as well as different trypanosome species in flies trapped in this focus.

Methods

Pyramidal traps were use to trap tsetse flies. All flies caught were identified and live flies were dissected and their mid-guts collected. Fly mid-gut was used for the molecular identification of the blood meal source, as well as for the presence of different trypanosome species.

Results

About 949 Glossina palpalis palpalis were trapped; 296 (31.2%) of which were dissected, 60 (20.3%) blood meals collected and 57 (19.3%) trypanosome infections identified. The infection rates were 13.4%, 5.1%, 3.5% and 0.4% for Trypanosoma congolense savannah type, Trypanosoma brucei s.l., Trypanosoma congolense forest type and Trypanosoma vivax, respectively. Three mixed infections including Trypanosoma brucei s.l. and Trypanosoma congolense savannah type, and one mixed infection of Trypanosoma vivax and Trypanosoma congolense savannah type were identified. Eleven Trypanosoma brucei gambiense infections were identified; indicating an active circulation of this trypanosome subspecies. Of all the identified blood meals, about 58.3% were identified as being taken on pigs, while 33.3% and 8.3% were from man and other mammals, respectively.

Conclusion

The presence of Trypanosoma brucei in tsetse mid-guts associated with human blood meals is indicative of an active transmission of this parasite between tsetse and man. The considerable number of pig blood meals combined with the circulation of Trypanosoma brucei gambiense in this focus suggests a transmission cycle involving humans and domestic animals and could hamper eradication strategies. The various species of trypanosomes identified in the Malanga sleeping sickness focus indicates the coexistence of animal and human African Trypanosomiasis. The development of new strategies integrating control measures for human and animal trypanosomiasis may enable the reduction of the control costs in this locality.

Keywords:
Sleeping sickness; Animal African trypanosomiasis; Trypanosomes; Blood meals; Tsetse flies; Mid-guts