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A global sensitivity analysis for African sleeping sickness

Published online by Cambridge University Press:  16 November 2010

STEPHEN DAVIS ,
SERAP AKSOY  and
ALISON GALVANI
STEPHEN DAVIS*
Affiliation:
Yale School of Public Health, 60 College Street, P.O. Box 208034, New Haven, CT 06520USA School of Mathematics and Geospatial Sciences, RMIT University, GPO Box 2476 V, Melbourne, Victoria 3001, Australia
SERAP AKSOY
Affiliation:
Yale School of Public Health, 60 College Street, P.O. Box 208034, New Haven, CT 06520USA
ALISON GALVANI
Affiliation:
Yale School of Public Health, 60 College Street, P.O. Box 208034, New Haven, CT 06520USA
*
*Corresponding author: School of Mathematical and Geospatial Sciences, Building 8, Level 9, Room 67, RMIT University, GPO Box 2476V, Melbourne, Victoria 3000, Australia. Tel: +61 (0)3 9925 2278. Fax: +61 (0)3 9925 2454. E-mail: [email protected]
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Summary

African sleeping sickness is a parasitic disease transmitted through the bites of tsetse flies of the genus Glossina. We constructed mechanistic models for the basic reproduction number, R0, of Trypanosoma brucei gambiense and Trypanosoma brucei rhodesiense, respectively the causative agents of West and East African human sleeping sickness. We present global sensitivity analyses of these models that rank the importance of the biological parameters that may explain variation in R0, using parameter ranges based on literature, field data and expertize out of Uganda. For West African sleeping sickness, our results indicate that the proportion of bloodmeals taken from humans by Glossina fuscipes fuscipes is the most important factor, suggesting that differences in the exposure of humans to tsetse are fundamental to the distribution of T. b. gambiense. The second ranked parameter for T. b. gambiense and the highest ranked for T. b. rhodesiense was the proportion of Glossina refractory to infection. This finding underlines the possible implications of recent work showing that nutritionally stressed tsetse are more susceptible to trypanosome infection, and provides broad support for control strategies in development that are aimed at increasing refractoriness in tsetse flies. We note though that for T. b. rhodesiense the population parameters for tsetse – species composition, survival and abundance – were ranked almost as highly as the proportion refractory, and that the model assumed regular treatment of livestock with trypanocides as an established practice in the areas of Uganda experiencing East African sleeping sickness.

Keywords

trypanosomiasisnext-generation matrixmathematical modelTrypanosoma brucei gambienseTrypanosoma brucei rhodesiense
Type
Research Article
Information
Parasitology , Volume 138 , Issue 4 , April 2011 , pp. 516 - 526
Copyright
Copyright © Cambridge University Press 2010

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