Mathematical modelling of the Ebola virus disease.
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Date
2024
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Abstract
Despite the numerous modelling efforts to advise public health physicians to understand
the dynamics of the Ebola virus disease (EVD) and control its spread, the disease
continued to spread in Africa. In the current thesis, we systematically review previous
EVD models. Further, we develop novel mathematical models to explore two important
problems during the 2018-2020 Kivu outbreak: the impact of geographically targeted
vaccinations (GTVs) and the interplay between the attacks on Ebola treatment centres
(ETCs) and the spread of EVD. In our systematic review, we identify many limitations in
the modelling literature and provide brief suggestions for future work. Our modelling
findings underscore the importance of considering GTVs in areas with high infections. In
particular, we find that implementing GTVs in regions with high infections so that the
total vaccinations are increased by 60% decreases the cumulative cases by 15%. On the
other hand, we need to increase the vaccinations to more than 1000% to achieve the 15%
decrease in EVD cases if we implement GTVs in areas with low infections. On the
impact of the attacks on ETCs, we find that due to the attacks on ETCs, the cumulative
cases increased by more than 17% during the 2018-2020 Kivu outbreak. We also find that
when 10% of the hospitalised individuals flee the attacks on ETCs after spending only
three days under treatment, the cumulative cases increased by more than 30% even if
these individuals all returned to the ETCs three days later. On the other hand, if only half
of these individuals returned to ETCs for treatment, the cumulative cases increase by
approximately 50%. Further, when these patients spend one more day in the community,
after which they all return to ETCs, the cumulative cases rise by an additional 10%.
Global sensitivity analysis also confirmed these findings. To conclude, our literature
systematic review is used to identify many critical factors which were overlooked in
previous EVD models. Our modelling findings show that the attacks on ETCs can be
destructive to the efforts of EVD response teams. Hence, it is important for
decision-makers to tackle the reasons for community distrust and address the roots of the
hostility towards ETCs. We also find that GTVs can be used to contain the spread of EVD when ring vaccinations, contact tracing and antiviral treatments cannot successfully control the spread of EVD.
Description
Doctoral Degree. University of KwaZulu-Natal, Durban.