HOW EBOLA SPREAD ACROSS SIERRA LEONE DURING THE 2014-2015 EPIDEMIC?
Understanding the growth and spatial expansion of (re)emerging infectious disease outbreaks, such as Ebola and avian influenza, is critical for the effective planning of control measures; however, such efforts are often compromised by data insufficiencies and observational errors. In this study, we develop a novel spatial-temporal inference methodology requiring only limited, readily compiled data and use this method to reconstruct the transmission network of the 2014-15 Ebola epidemic in Sierra Leone. Transmission within the network introduced Ebola to new regions and initiated self-sustaining local epidemics. Two major transmission pathways are inferred, facilitated by two of the more populous and connected districts, Kenema and Port Loko. Epidemic intensity differed by district, correlated with population size, and a critical window of opportunity for containing local Ebola epidemics at the source (ca. one month) existed. This novel methodology can be used to help identify and contain the spatial expansion of future (re)emerging infectious disease outbreaks.
Yang W, Zhang W, Kargbo D, Yang R, Chen Y, Chen Z, Kamara A, Kargbo B, Kandula S, Karspeck A, Liu C, Shaman J. 2015. Transmission network of the 2014-2015Ebola epidemic in Sierra Leone. Journal of the Royal Society Interface. Published 11 November 2015. DOI: 10.1098/rsif.2015.0536.
INFERENCE AND FORECAST OF EBOLA OUTBREAKS IN GUINEA, LIBERIA, AND SIERRA LEONE
The 2014-15 Ebola epidemic in three West African countries—Guinea, Liberia, and Sierra Leone, is the largest on record. WHO declared the outbreak a Public Health Emergency of International Concern on 8 August 2014. We started to work on the project in early August 2014. Since then, we have tested a variety of epidemic models for Ebola transmission and used them to forecast the epidemic in the three countries. Near real-time weekly forecasts have been posted on our forecast website (http://cpid.iri.columbia.edu) since October 2014. We have also studied the epidemiological characteristics of the current Ebola epidemic, including the basic reproductive number, incubation period, and infectious period.
Shaman J, Yang W, Kandula S. Inference and forecast of the current West African Ebola outbreak in Guinea, Sierra Leone and Liberia. PLOS Currents: Outbreaks Oct 31, Edition 1 (2014). doi: 10.1371/currents.outbreaks.3408774290b1a0f2dd7cae877c8b8ff6.