There’s no foolproof way to screen airline passengers for a disease like Ebola that lies dormant and undetectable for days.
While enhanced screening announced yesterday for New York’s John F. Kennedy and four other U.S. airports will help stem the disease’s spread and assuage public fears, it’s an imperfect defense against a complex public health emergency, said Lawrence Gostin, a professor of global health law at Georgetown University in Washington.
The reliability of screening arriving passengers rests largely on travelers being honest about whether they have come in contact with others infected with Ebola. And tricks as simple as taking Tylenol before landing to help ensure they can pass a fever test when going through Customs have been used by passengers before, such as during the 2003 SARS virus outbreak.
“If the goal is 100 percent effectiveness in terms of keeping Ebola patients out of the country, this won’t work,” Anish Jha, a professor at the Harvard School of Public Health in Boston, said in an interview. The increased screening “is a step in the right direction but it’s hardly foolproof.”
Health officials have vowed to stop any spread in the U.S. of the virus, which has a fatality rate of about 50 percent and is transmitted by direct contact with a sick person’s blood or other bodily fluids. Passengers whose travel originated in Liberia, Sierra Leone and Guinea will be visually assessed upon arrival to the U.S., have their temperatures taken and asked if they had any contact with people infected with Ebola.
Early signs of the disease are a fever and flu-like symptoms. There’s also a risk that the tests ensnare people without the deadly disease, Gostin said.
“There will still be many false positives,” he said. “Most patients with a fever will have influenza, malaria, tuberculosis or another disease.”
Airport screening is likely to yield few results, while costing millions, said Mark Gendreau, who was part of a Federal Aviation Administration-sponsored study last year on reducing the threat from infectious diseases in airports.
Chinese officials once tracked the transmission of the swine flu, or H1N1, to an airline passenger who lied to an airport screener. Attempts to screen for severe acute respiratory syndrome, or SARS, on airlines have turned up a few positive cases relative to the costs, Gendreau said.
“It’s incredibly expensive and incredibly ineffective,” said Gendreau, who is now vice chairman ofemergency services at Lahey Hospital & Medical Center in Burlington, Massachusetts.
The White House said that fighting the disease in West Africa is still the primary strategy in keeping the virus from spreading to the U.S.
“Preventing individuals who are already exhibiting symptoms of Ebola from boarding a plane in the first place is the most effective measure that will counter and has countered the spread of Ebola,”Josh Earnest, a White House spokesman, told reporters yesterday.
Passengers leaving Monrovia, Liberia, on international flights must wash their hands twice with chlorinated water before boarding, get their temperatures taken at a security gate and fill out a form indicating if they had contact with someone who had the disease. Duncan failed to disclose that he had that contact, according to the Liberian government, which said on a Twitter account before he died that it would charge him with making a false declaration.
Ebola has killed more than 3,800 people in West Africa, prompting the U.S. to send as many as 4,000 military personnel to the region to build treatment centers and train health-care workers. President Barack Obama has committed to spend as much as $1 billion.
U.S. agents have the ability to track passengers’ full itinerary, even if they travel from Africa toEurope on separate tickets before coming to the U.S., according to Homeland Security Deputy Secretary Alejandro Mayorkas.
Fewer than 150 people, or less than 0.1 percent of 275,000 daily airborne travelers to the U.S., come from the three countries affected. The five airports with the new screenings accounted for 94 percent of travelers from the affected region.
“We think that air travel is totally safe and people should keep getting on airplanes if you look at the facts of how the disease is transmitted,” Nicholas Calio, president of Washington-based trade group Airlines for America, said today.
Only two U.S. airlines, United and Delta Air Lines Inc., offer Africa nonstop service, and neither flies to any of the countries in the Ebola-outbreak zone. Delta halted flights to Monrovia in August.
Separately, the U.S. Coast Guard in Long Island issued a notice to incoming ships that they must disclose if someone on board is sick with Ebola symptoms. The notice, sent this week, is more specific than the general nationwide guidance the Coast Guard issued in August.
Tom Frieden, director of the Centers for Disease Control and Prevention, said that the reaction to the 2003 outbreak of severe acute respiratory syndrome virus, or SARS, cost the global economy $40 billion, not because of the disease but because of the reaction to it.
“If we don’t ensure that we focus on what works, we may have that same kind of overreaction,” he said.
An analysis of border screening for SARS, which unlike Ebola can be transmitted through the air, found that border screening played a “relatively minor role” in reducing the disease spread. In Australia, 1.84 million people arrived in the months of 2003 when that nation tested for fevers and, of those, 794 were referred for screening. None of these people was confirmed to have SARS, according to a study by researchers from the Australian Department of Health and Aging.
Even if procedures at airports don’t find any cases of Ebola, they can be an important symbolic service, Gostin said.
“There is intense political pressure to be seen doing something,” he said.