Between August and November 2014, the incidence of Ebola virus disease
(EVD) rose dramatically in several districts of Sierra Leone. As a
result, the number of cases exceeded the capacity of Ebola holding and
treatment centres. During December, additional beds were introduced, and
incidence declined in many areas. The research aimed to measure patterns
of transmission in different regions, and evaluate whether bed capacity
is now sufficient to meet future demand.
A mathematical model of EVD infection was used to estimate how the
extent of transmission in the nine worst affected districts of Sierra
Leone changed between 10th August 2014 and 18th January 2015. Using the
model, the research forecast the number of cases that could occur until
the end of March 2015, and compared bed requirements with expected
It was found that the reproduction number, R, defined as the average
number of secondary cases generated by a typical infectious individual,
declined between August and December in all districts. It was estimated
that R was near the crucial control threshold value of 1 in December.
They further estimated that bed capacity has lagged behind demand
between August and December for most districts, but as a consequence of
the decline in transmission, control measures caught up with the
epidemic in early 2015.
EVD incidence has exhibited substantial temporal and geographical
variation in Sierra Leone, but our results suggest that the epidemic may
have now peaked in Sierra Leone, and that current bed capacity appears
to be sufficient to keep the epidemic under-control in most districts.
Camacho, A.; Kucharski, A.; Aki-Sawyerr, Y.; White, M.A.; Flasche, S.; Baguelin, M.; Pollington, T.; Carney, J.R.; Glover, R.; Smout, E.; Tiffany, A.; Edmunds, W.J.; Funk, S. Temporal Changes in Ebola Transmission in Sierra Leone and Implications for Control Requirements: a Real-time Modelling Study. PLoS Currents (2015) : [DOI: 10.1371/currents.outbreaks.406ae55e83ec0b5193e30856b9235ed2]
Temporal Changes in Ebola Transmission in Sierra Leone and Implications for Control Requirements: a Real-time Modelling Study