Travelers at Los Angeles International Airport prepare to check in before their flights on Thanksgiving Day 2009.
Travelers at Los Angeles International Airport prepare to check in before their flights on Thanksgiving Day 2009. // Nick Ut/AP

There’s Really No Way To Screen for Ebola at Airports

On Thursday, the Nigerian government announced that they had started screening passengers at international airports for signs of Ebola after a passenger showed up in Lagos suffering from the illness, which kills up to 90 percent of the people infected with it. Treatment options are extremely limited. Nigerian airport authorities will be checking passengers who just arrived from Sierra Leone, currently under a state of emergency, and they’ll be looking for fever, since an elevated temperature is considered a sign of Ebola. If the passenger is presenting with higher than normal temperatures, screeners would subject the passenger to a blood test.

Ebola is moving into more countries across Africa, but not as quickly as is fear. The country of South Africa announced Thursday that they were in the process of outfitting airports with thermal scanners to detect feverish passengers.  In many ways, it’s a repeat of 2009, when airports around the world brought in thermal scanners to look for passengers who were presenting with fever and suspected bird flu.  

The recent Ebola outbreak has already arrived in the United States, under careful observation. The CDC confirmed that at least one Ebola victim, Kent Brantly arrived back in the United States this weekend. Brantly, of Fort Worth, Texas, was working to staunch the outbreak in Liberia when he picked up the illness.

All I am aware of, in terms of U.S. military involvement, is that we have a couple of Army researchers down in Africa, in Liberia, right now who have been for some time working on this particular virus,” Kirby said.

The good news is that neither the White House nor the epidemiologists that spoke to Defense One expects Ebola to have nearly as deadly an effect in the U.S. as it is having in Africa, where more than 729 people have already died.

The bad news is that thermal screenings of the international flying population at airports are not likely to yield much by way of improved safety.

Here’s why: fever can be a sign of a lot of different illnesses, not just Ebola. And thermal scanning proved to be a poor method of catching bird flu carriers in 2009 as well. So presenting with an elevated temperature at an airport checkpoint does not indicate clearly enough that the fevered person is carrying the deadly virus. More importantly, the incubation period for Ebola is two days. As many as 20 days can pass before symptoms show up. That means that an individual could be carrying the virus for two weeks or longer and not even know it, much less have it show up via thermal scan. So what good are these scanners?

“I think that thermal screeners help people feel safe,” Dr. Noreen Hynes with the Johns Hopkins Bloomberg School of Public Health told Defense One.

The second method that the Nigerian government is taking to detect the presence of Ebola in—possibly—feverish passengers is a blood test. The presence of antibodies in the blood is a much more conclusive sign of the deadly virus. Unfortunately, subjecting hundreds or possibly thousands of passengers to a blood test for Ebola would be practically impossible in a major airport without slowing International air travel to a halt. The current method for performing one of these tests, also called a polymerase chain reaction test, can take eight hours or longer, requires results to be sent to a lab, and is prohibitively expensive in many cases.

Experts agreed that a test able to reveal the presence of Ebola on location at an airport checkpoint—and do so in a relatively short amount of time—would greatly improve authorities’ ability to stop the virus from crossing international borders. One person working on that is Douglass Simpson, CEO of Corgenix, which in June received a $3 million National Institutes of Health grant to develop a point-of-care test for Ebola. Airport screeners would use it to spot the virus in a feverish passenger in just ten minutes at airports. “Our job is to as quickly as possible advance those tests and make them available in those zones,” Simpson said.

It’s exactly the sort of thing that could provide much more conclusive evidence of a passenger with Ebola. But it won’t be in the hands of airport screeners for years. “We’re several years from getting it completed,” says Simpson. He hopes that Corgenix will have a rapid test for Ebola by 2016.

What do we have to protect us today? The same thing we have to protect us from dangerous terrorist masterminds: background screening.

Because the population of people who have this illness are relatively small and we have some idea of the areas that have been exposed, Ebola is an example of a threat that could be better managed at airports by picking out those people who were most likely to have encountered the disease based on where they had been.

“The nature of Ebola makes it similar to, but also different than traditional aviation threats.  Aviation security protects against the flight on hand, while screening for Ebola has a longer footprint to display and protect,” Sheldon H. Jacobson, a professor of computer science at the University of Illinois, told Defense One.

It’s a subject that he knows a lot about. In 2012, his paper Addressing Passenger Risk Uncertainty for Aviation Security Screening effectively showed that too much random screening at airports was making TSA and border agents less effective at their jobs. The guards were scanning, patting, and focusing on people who posed no real threat, effectively de-sensitizing them to people who may have had more intent and capacity to commit harm. “A natural tendency, when limited information is available about from where the next threat will come, is to overestimate the overall risk in the system,” Jacobson said in a statement around the time of the paper’s release. “This actually makes the system less secure by over-allocating security resources to those in the system that are low on the risk scale relative to others in the system.”

Pre-screening passengers for Ebola on the basis of where the passenger has been and the likelihood of coming into contact with the disease is probably a more effective means to catch it than is trying to take the temperature of thousands of people with a camera, according to Jacobson. “Prescreening would be prudent, and reasonable, based on the information available. Public health personnel would need to develop appropriate criteria that yield good results and also limit false positives.  In essence, prescreening, if done appropriately, can work in any type of screening mechanism,” he wrote to Defense One in an email.

Ebola is passed through fluids such as blood and so health care workers treating infected populations, and doing so in less than ideal settings like clinics in Sierra Leone, are the most vulnerable. Hynes says that’s one reason you aren’t at much less risk.  

(Of course, in most cinematic depictions of a zombie outbreak, zombieism is also passed via fluids, and, as in the case of Ebola, carriers are ambulatory, or walking, for long periods of time. Published modeling has shown that a zombie outbreak would spread across a major city like Lagos in a period of four days. But zombieism, as depicted fictionally, is also accompanied by psychotic cannibalism, which serves as an accelerant to spread. Ebola is accompanied by malaise, which has the opposite effect.)

Hynes acknowledges that while the U.S. won’t become like Sierra Leone, more people will be getting the illness in the months ahead. “Right now the trajectory is still in the upward mode,” she said.

The issue of Ebola slipping into the United States is part of the broader, hotter discussion on border control, which entails everything from keeping potential terrorists out of the country to detecting nuclear weapons, to housing, processing and caring for the some 57,000 immigrant children who have crossed into the country illegally since Oct. 1. These are all fundamentally different challenges. Some pose mortal threats, others do not. But from a political perspective they share the border in common. That can lead to politicians who want to treat every incursion over the border with equal alarm, as Rep. Michelle Bachman, R-Minn., effectively did the other day, claiming the country’s Southern border was an open invitation. “Not only people with potentially terrorist activities, but also very dangerous weapons are going to cross our border in addition to very dangerous drugs, and also life-threatening diseases, potentially including Ebola and other diseases like that.”

On Thursday, a subcommittee of the House Committee on Science, Space and Technology tackled the issue in a special hearing on the technology needed to secure America’s border. The hearing did not touch on Ebola, but the panelists were largely in agreement on one key point — the Department of Homeland Security has no effective means for evaluating the deployment of border technology.

While point-of-care tests for Ebola won’t be deployable for at least two years, biometric facial recognition technology and other security screening technologies to detect identity are far more advanced, but they have yet to be fully implemented.  “The technologies are good and mature. I think one of the areas where [The Department of Homeland Security] DHS struggles is tooth to tail. Where do you have people to back up and integrate with technology to make the best effective use of it. DHS acquisition processes are maturing…but are not perfect,” Jack Riley, the director of the RAND National Defense Research Institute, testified.

“We worked on an evaluation for a technology for biometric identification at airports. The technology was quite ready. It was off the shelf.  It was effective. The problem was it couldn’t be integrated into the human systems,” testified Joseph D. Eyerman, the director for research and management at the Institute for Homeland Security Solutions at Duke University, meaning that human airport screeners couldn’t use the data from the facial recognition systems, for a variety of reasons.

How to make sure screening technology is implemented at airports and other checkpoint is no simple matter, but it could become one. Riley suggested that a border czar could help make sure that the technology to catch nuclear weapons, and perhaps Ebola, isn’t misspent screening immigrant children who are very unlikely to be harboring either.  “We need a single point of accountability on the border so that we can begin to understand some of these large tradeoffs,” Riley told Defense One.  

When asked by committee chairman Rep. Lamar Smith, R-Texas, how they would rate Department of Homeland Security’s use of border technology, the witnesses answered uniformly: “Incomplete.”

Despite centuries of progress, in many ways, our ability to catch disease at a border hasn’t changed much since 1374, when the Black Death was laying waste to populations of Europe. It was at this time that the Doge of Venice put in place a protocol to attempt to arrest the disease in port. He created three so-called Guardians of Health. They were health screeners and their job was to board ships in port and inspect crew for inflamed lymph nodes. If symptoms were found, or suspected aboard the crew, the Guardian would order the ship away from port for a period of forty days, quaranta giorni.

Not enough has changed. The current Ebola outbreak is unlikely to claim the lives of hundreds of Americans, and will likely run its course before summer of next year. The question of how to catch diseases at the border is not going to go away. But because of our innate tendency to “overestimate the overall risk in the system,” we will be inclined to treat every incursion over the border as an equal threat. The next time a major outbreak hits, technology to detect it will be more advanced. Our ability to implement that technology may not be. 

This post has been updated.

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