Exit screening is essential to prevent Ebola-infected travelers leaving on international flights from affected countries like Guinea, Liberia and Sierra Leone, says a new study.
Dr Kamran Khan at St Michael's Hospital in Toronto, Canada, and colleagues, who analysed 2014 worldwide flight schedules and historic flight itineraries of passengers from 2013 to predict expected population movements out of Guinea, Liberia, and Sierra Leone, found that based on current epidemic conditions and international flight restrictions to and from Guinea, Liberia, and Sierra Leone, on average, just under three travellers infected with Ebola virus are projected to travel on an international flight every month.
Although airport screening is currently in place in the locations modelled, the research draws attention to the importance of ensuring that exit screening is implemented and maintained effectively in these locations.
Dr Khan said that the risk of international spread could increase significantly if the outbreak in West Africa persists and grows and risks to the global community would further increase if Ebola virus were to spread to and within other countries with weak public health systems.
The findings also indicate that it is far more efficient and less disruptive to screen travellers for Ebola as they leave affected countries in West Africa rather than screen the same travellers as they arrive at other airports around the world. The authors also point out that with effective exit screening of travellers in place, the additional utility of entry screening is very low given the short flight durations out of affected countries, compared with the much longer incubation period of Ebola virus.
The researchers added that the best approach to minimise risks to the global community is to control the epidemic at its source. While screening travellers arriving at airports outside of West Africa may offer a sense of security, this would have at best marginal benefits, and could draw valuable resources away from more effective public health interventions.
They also said that excessive constraints on air travel could have severe economic consequences that could destabilise the region and possibly disrupt critical supplies of essential health and humanitarian services. Decision-makers must carefully balance the potential harms that could result from travel restrictions against any reductions in the risk of international spread.
The study was published in The Lancet.