Consequences of short term mobility across heterogeneous risk environments: the 2014 west African Ebola outbreak

In this dissertation the potential impact of some social, cultural and economic factors on

Ebola Virus Disease (EVD) dynamics and control are studied. In Chapter two, the inability

to detect and isolate a large fraction of EVD-infected individuals before symptoms onset is

addressed. A mathematical model, calibrated with data from the 2014 West African outbreak,

is used to show the dynamics of EVD control under various quarantine and isolation

effectiveness regimes. It is shown that in order to make a difference it must reach a high

proportion of the infected population. The effect of EVD-dead bodies has been incorporated

in the quarantine effectiveness. In Chapter four, the potential impact of differential

risk is assessed. A two-patch model without explicitly incorporate quarantine is used to

assess the impact of mobility on communities at risk of EVD. It is shown that the

overall EVD burden may lessen when mobility in this artificial high-low risk society is allowed.

The cost that individuals in the low-risk patch must pay, as measured by secondary

cases is highlighted. In Chapter five a model explicitly incorporating patch-specific quarantine

levels is used to show that quarantine a large enough proportion of the population

under effective isolation leads to a measurable reduction of secondary cases in the presence

of mobility. It is shown that sharing limited resources can improve the effectiveness of

EVD effective control in the two-patch high-low risk system. Identifying the conditions

under which the low-risk community would be willing to accept the increases in EVD risk,

needed to reduce the total number of secondary cases in a community composed of two

patches with highly differentiated risks has not been addressed. In summary, this dissertation

looks at EVD dynamics within an idealized highly polarized world where resources

are primarily in the hands of a low-risk community – a community of lower density, higher

levels of education and reasonable health services – that shares a “border” with a high-risk

community that lacks minimal resources to survive an EVD outbreak.