A new study predicts that three Ebola-infected people from West Africa will try and board an international flight every month — and more than 60 per cent of travellers from the outbreak zone will fly to lower-income countries with weak health-care systems.
But the study, led by Toronto researchers, also found that airport screening measures are far more likely to catch infected passengers at their departure points than at arrival airports, especially when their destinations are countries like Canada, which receive relatively few travellers from the region.
“I think we’re seeing a lot of countries implement entry screening even though there are no direct flights,” said the paper’s senior author, Dr. Kamran Khan, an infectious disease physician and scientist with St. Michael’s Hospital. “It’s not a particularly efficient thing to do . . . and it’s potentially drawing resources away from other areas that might be more productive.”
Recent Ebola cases in Spain and the United States have triggered alarm over the virus’s ability to spread through international travel and a number of countries have started screening arriving passengers, a measure that is not currently recommended by the World Health Organization.
Governments in Canada and the United States, for example, have recently implemented mandatory health screenings and temperature checks for tourists arriving from Ebola-affected countries. Meanwhile, Western countries, including Canada, are still reluctant to send medical teams, which emergency responders have identified as West Africa’s most urgent need.
“At this time, we are not going to be sending any more medical personnel until we feel strongly that we have a guaranteed medical evacuation (for them),” Health Minister Rona Ambrose said in a news conference Monday. “We are exploring every option possible.”
The new study, published on Monday in The Lancet, analyzed just how effective such entry screening measures will be. Drawing from 2013 travel records and upcoming flight schedules, along with epidemiological data from the outbreak, the researchers also predicted which countries are at greatest risk of receiving an infected traveller.
They found that the world “should expect more exportations in the weeks and months ahead,” Khan said. Their projections showed that an average of 2.8 Ebola-infected travellers will board an international flight every month in Guinea, Liberia or Sierra Leone, the three countries at the heart of the epidemic, if there are no exit screening procedures in place.
Of course, all three countries are currently screening passengers, but those who are asymptomatic can still slip through, as was the case with Thomas Duncan, the Liberian man who was diagnosed with Ebola eight days after arriving in the United States.
Between September and December 2013, the top two destinations for travellers from the Ebola-affected countries were Ghana and Senegal, which together received 32 per cent of total passengers. These countries were followed by the United Kingdom and France, which received about 9 and 7 per cent, respectively.
Canadian airports, however, received only 1,299 visitors from the outbreak region, less than 10 per cent of the total travel volume. Of those, the highest number of travellers, 44 per cent, landed in Montreal, followed by 21 per cent who flew to Toronto.
But Khan is far more concerned about the countries receiving 64 per cent of total passengers, all of which are low-income to lower- middle-income nations with poorly resourced health systems that “might be unable to detect and adequately manage an imported case.”
For example, in Ghana, where most travellers from the Ebola-affected countries visited last year, there is only one doctor for every 10,000 people.
“I think this is an important concern about where this virus could end up, how capable these countries are in managing a potential case,” Khan said.
When comparing the effectiveness of exit and entry screening, the study also found that the former would allow health officials to assess all departing passengers, a far more efficient strategy than trying to detect infected passengers as they landed at one of the 15 countries receiving direct flights from the outbreak zone.
Trying to detect cases at airports that don’t receive direct flights is even more inefficient, Khan said. Over the next few months, an average of 2,512 travellers will need to be checked across 1,238 cities in order to identify just one person from the Ebola-affected region, who may not even be infected.
“That’s clearly less efficient and more challenging from an operational standpoint,” Khan said, adding that the international community should help Ebola-stricken countries strengthen their exit screening.
Khan acknowledges that his study has a number of weaknesses; it makes several assumptions and the epidemiological data is evolving rapidly along with the outbreak.
But given the urgency of the crisis, he and his co-authors wanted to take an objective look at the usefulness of screening measures now being adopted by an increasing number of countries. And while many people are calling for travel bans in and out of West Africa, Khan strongly believes they are not the answer.
“Ultimately, I think that would set back the effort and increase the risk of having this spread even further,” he said. “The most proactive way of preventing international spread is to get the outbreak under control in the source area.”
To date, Canada has pledged $65 million towards the outbreak response, with Ontario announcing another $3 million on Monday. The Public Health Agency of Canada has also sent personal protective gear, experimental vaccine, and a mobile laboratory for diagnosing cases in Sierra Leone.