October 21,2014
Researchers said the best way to prevent Ebola from spreading from West Africa is to do a better job of controlling it at the source. They said while exit and entry screening at airports is helpful, it cannot replace stemming the number of new infections.
The Lancet has published a new research paper that says, “Every month, three Ebola-infected people are likely to leave West Africa through air travel.” It warns that “if the epidemic persists and grows, it’s likely there will be more cases…exported to other countries.” The conclusions are based on flight itineraries, flight cancelations and the number of new infections in Guinea, Liberia and Sierra Leone.
Dr. Kamran Khan is one of the authors and is an infectious disease specialist and physician at St. Michael’s Hospital in Toronto. He said there are potentially three different places to intervene in the Ebola crisis.
“One, you can do this in your own country if you’re unfortunate enough to receive an imported case of Ebola. You know, that obviously is not the ideal situation because there is clearly health and economic and even psychological impacts that can result from an imported case as we’re currently seeing in the U.S. The second area you can focus on: travelers, who might be inadvertently moving Ebola virus to different parts of the globe.”
Researchers studied how efficient or inefficient it was to screen travelers before they left West Africa and when they arrived in other countries.
“What we found was that you could actually screen all of the travelers that would be at high risk of being potentially exposed to Ebola virus just from three airports in West Africa. And the additional benefit of screening at the entry side when they’re arriving in other countries is expected to be quite low because the travel times are fairly short and the incubation period – this is the time from which an individual is exposed to the time that they develop symptoms – is on average 8-to-10 days. [It] can be as long as 21-days.” Khan said.
He said the combination of exit and entry screening probably will not make much of a difference overall. But he added, stopping just one case helps.
“I don’t think that there is any significant harm from having that type of intervention take place. It’s just that it’s not likely to have a really meaningful impact in minimizing the spread of disease. And so, finally, really, the only other frontier, the other option, is to decrease the number of new infections in the source countries themselves.”
Khan and his colleagues tried to predict the places where Ebola might spread if the outbreak is not contained.
He said, “Roughly two-thirds of all of the travelers – their final destinations are expected to be low-income or lower-middle-income countries. And I think that’s particularly notable given that the capacity of these countries to quickly detect and control and respond to a possible imported case of Ebola virus isn’t going to be as robust as it would be in other more industrialized countries.”
He said that imposing travel bans to the U.S., Canada and other developed countries is not the answer as some would believe.
“I know there’s certainly been a lot of very heated debate over the issue of travel bans. Those are really just addressing the symptom. They’re not actually taking care of the root cause. So, if anything, they’re really just going to have either a very short benefit or a very marginal benefit,” he said.
Some U.S. lawmakers and others have said a travel ban can be imposed, while at the same time exempting humanitarian workers and aid flights.
Khan said, “Certainly, the capacity of bringing in medical supplies and certain humanitarian supplies through noncommercial flights is an option. But [considering] the scale of all of the goods and services that flow into a country – I’m not convinced that that actually is possible -- at least not a very feasible option. If we just think for a moment what would happen if all flights were canceled into the United States, you would see tremendous economic consequences – impacts on things like food supplies and fuel and all of these other types of important product s and services.”
Dr. Khan said it all comes back to addressing the source of the problem.
“Really what we need to do is change the shape of the epidemic curve. And that basically just means rather than seeing increasing numbers of new infections we need to actually turn this around so the number of new infections in the population is decreasing. And that’s going to really require more intensive resources in the three affected countries, health care personnel, personal protective equipment, medical supplies.”
He said that of nearly 500,000 travelers who flew on commercial flights out of Guinea, Liberia and Sierra Leone in 2013, more than half were headed to five countries: Ghana, Senegal, Britain, France and the Gambia.