2021/01/12(Tue) 10:30 -11:30 視訊會議室(圖書館) 3F, Video Conference Room(Library)
Title
Is sleeping sickness eliminable? Insights from mathematical modelling
Speaker
Dr. Ching-I Huang (Mathematics Institute, University of Warwick, UK.)Abstract
Gambiense human African trypanosomiasis (gHAT, sleeping sickness) is a virulent disease
declining in burden but still endemic in West and Central Africa. Although it is targeted for
elimination of transmission by 2030, there remain numerous questions such as the drivers
of infection, how these vary geographically, where intensified interventions are needed, and
what are the cost-effectiveness strategies for eliminating gHAT in different regions.
We focus on the Democratic Republic of Congo (DRC), which accounted for 84% of the
global case burden in 2016, to explore changes in transmission across the country and
elucidate factors which may have contributed to the persistence of disease or success of
interventions in different regions. We present a Bayesian fitting methodology, applied to
168 endemic health zones (~100,000 population size), which allows for calibration of a
mechanistic gHAT model to case data (from the World Health Organization HAT Atlas) in an
adaptive and automated framework.
The fitted model in DRC was used to predict cases and new infections under four future
strategies all endemic health zones. The strategies comprise of medical interventions –
active and passive screening (AS and PS) – and some include large-scale vector control (VC).
In each health zone, we estimate the median year of EOT and the probability of EOT by 2030
under each and compute the least ambitious strategy predicted to achieve EOT by 2030.
We further compared four strategies against gHAT by coupling a transmission model with a
health outcomes model in five settings – spanning low- to high-risk. A scale-back algorithm
was devised to simulate cessation of AS and VC when no cases were reported for three
consecutive years. Outcomes were denominated in disability-adjusted life-years (DALYs) and
costs until 2040 were denominated in 2018 US$.
Our fitted model suggests that underlying transmission has reduced greatly – 89% - 96% in
Bas Congo, Bandundu, and Equateur provinces where having had the highest case burdens
in 2000. Model projections provide a priority list for consideration for supplementary VC
implementation (Bagata, Bandundu, Bolobo, Kikongo, Kwamouth and Masi Manimba in
Bandundu province) in conjunction with the recent AS coverage to achieve the elimination
of transmission by 2030. Economic evaluation in five distinct transmission settings shows
that costs of gHAT strategies are primarily driven by AS and, if used, VC in high or moderate-
risk settings. Due to the cessation of AS and VC most investments (75-80\%) will be made by
2030 and VC might be cost-saving while ensuring EOT. In low-risk settings, costs are driven
by PS, and minimum-cost strategies consisting of AS and PS lead to EOT by 2030 with high
probability.
Language
演講語言 (Language): in English