Modeling framework to demonstrate elimination of a vector population: Tsetse elimination in Chad

Publication Type

Journal Article

Journal Name

Proceedings of the National Academy of Sciences of the United States of America

Name of Author

• John Hargrove, Stellenbosch University
• Mahamat Hissene Mahamat, Institut de Recherche en Elevage pour le Développement (IRED)
• Moukhtar Aldjibert, Institut de Recherche en Elevage pour le Développement (IRED)
• Wilfrid Yoni, CIRDES (Centre International de recherche-développement sur l'élevage en zone subhumide)
• Djoukzoumka Signaboubo, Institut de Recherche en Elevage pour le Développement (IRED)
• Justin Darnas, Programme National de Lutte contre la Trypanosomiase Humaine Africaine
• Ernest Salou, CIRDES (Centre International de recherche-développement sur l'élevage en zone subhumide)
• Inaki Tirados, Liverpool School of Tropical Medicine
• Albert Mugenyi, Ministry of Agriculture Animal Industry and Fisheries
• Priscille Barreaux, International Centre of Insect Physiology and Ecology Nairobi
• Philippe Solano, Université de Montpellier
• Antoine Marc Gaby Barreaux, Université de Montpellier

Publication Date

6-30-2026

Abstract

Every year, over 700,000 people, particularly children under five, die from vector-borne diseases worldwide. Effectively controlling endemics and preventing new outbreaks requires an integrated approach that can lead to the elimination of both vectors and diseases. In the last two decades, integrating medical interventions and vector control has significantly reduced the incidence of Gambian Human African Trypanosomiasis (g-HAT), with the World Health Organization validating eight countries as having eliminated the disease as a public health problem. However, elimination of the tsetse vector has not been confirmed, leaving the possibility of re-emergence. We developed a six-step modeling framework to assess vector elimination by calculating: i) the probability of vector capture; ii) the probability of observing a series of zero catches, even without actual elimination; iii) the probability of natural elimination; iv) the probability of failing to detect a rebound; v) the reinvasion risk; and vi) the sensitivity analysis. Our case study is g-HAT in Mandoul, Chad, and the elimination of Glossina fuscipes fuscipes. We used vector control from 2014 to 2025 with no tsetse detected since 2018. We cannot yet conclude, with over 90% confidence, that tsetse has been eliminated from Mandoul, nor that any remnant population will be naturally eliminated. However, since vector control stopped in April 2025, we estimate that with continued sampling over the next 2 y, and no tsetse detected, elimination could be demonstrated with 99% confidence. Our multistep modeling framework can be applied to other vectors, providing policymakers with guidelines for ongoing and future efforts.

Keywords

elimination, mathematical modeling, public health policy, vector control, vector-borne disease

Recommended Citation

Hargrove, J., Mahamat, M., Aldjibert, M., Yoni, W., Signaboubo, D., Darnas, J., Salou, E., Tirados, I., Mugenyi, A., Barreaux, P., Solano, P., & Barreaux, A. (2026). Modeling framework to demonstrate elimination of a vector population: Tsetse elimination in Chad. Proceedings of the National Academy of Sciences of the United States of America, 123 (26) https://doi.org/10.1073/pnas.2524729123