Ebola virus disease outbreak in Nigeria: lessons to learn

Abstract

International air travel has already spread Ebola virus disease (EVD) to major cities as part of the unprecedented epidemic that started in Guinea in December 2013. An infected airline passenger arrived in Nigeria on July 20, 2014 and caused an outbreak in Lagos and then Port Harcourt. After a total of 20 reported cases, including 8 deaths, Nigeria was declared EVD free on October 20, 2014. We quantified the impact of early control measures in preventing further spread of EVD in Nigeria and calculated the risk that a single undetected case will cause a new outbreak. We fitted an EVD transmission model to data from the outbreak in Nigeria and estimated the basic reproduction number R 0 = 9.0 (95% confidence interval [CI]: 5.2-15.6). We also found that the net reproduction number R t fell below unity 15 days (95% CI: 11-21 days) after the arrival of the index case. Using the estimated value of R 0 in Nigeria, we calculated that the risk of an outbreak from a single undetected case was 89% (95% CI: 81-94%). Even though R 0 in Nigeria was high, EVD outbreaks caused by infected air travelers can be successfully contained if control measures are rapidly implemented.

Theoretical perspectives on the infectiousness of Ebola virus disease

“…Owing to the rapid progression of the EVD epidemic in West Africa, attempts have been made to clarify the fundamental epidemiological characteristics of EVD [ 1 , 2 , 4 ]. For instance, several studies have reported statistical estimates of the reproduction number, i.e., the average number of secondary cases generated by a single primary case, as a measure of the transmission potential of EVD [ 2 , 5 – 12 ]. Despite substantial progress, it remains unclear how measures of infectiousness (or the transmissibility) of EVD should be communicated to the public and interpreted in light of the set of control interventions that could be considered in practical settings.…”

Conditions for Endemicity: Qualitative Population Dynamics in a Long-running Outbreak of Ebola Virus Disease

“…The spirit of this approach has been revisited to describe disease dynamics in the 2013-2016 West African EVD epidemic, and in other filoviral outbreaks. Models from Brozek (2011); Gomes et al (2014), Rivers, Lofgren, Marathe, Eubank, andLewis (2014), Camacho et al (2014), Althaus, Gsteiger, and Low (2014), Lewnard et al (2014), Pandey et al (2014) and Weitz and Dushoff (2015) each track the effect of postmortem infection in filoviral epidemics via systems with an explicit deceased-infectious compartment. One excellent review of several of these models is from Chowell and Nishiura (2014).…”

“…We begin with a deceased-infectious (SEIRD-type) model similar to several proposed above (Brozek, 2011;Althaus et al, 2014;Weitz & Dushoff, 2015). Susceptible individuals (S) who become infected move into an exposed class (E).…”