Year of airport screening doesn't catch Ebola

Federal authorities, who screened more than 30,000 travelers for Ebola as they arrived at airports from West African countries over the past year, never detected a case of the often fatal disease. At least one person incubating the disease -- but not yet showing symptoms -- slipped into the country without drawing notice.

Calls for airport screenings and quarantines arose after Thomas Eric Duncan, 42, became ill from Ebola after arriving in Dallas on Sept. 20, 2014, from Liberia. Doctors diagnosed Duncan on Sept. 30 and he died Oct. 8. Beginning Oct. 11, 2014, the Department of Homeland Security's Customs and Border Protection launched the extra screening at five airports – New York’s John F. Kennedy, New Jersey’s Newark, Chicago O’Hare, Washington Dulles and Atlanta Hartsfield-Jackson – for travelers arriving from Liberia, Sierra Leone and Guinea. The airports handle 94% of the travelers arriving from those countries at the center of the outbreak.

CBP reported 30,982 travelers received extra screening from Oct. 11, 2014 through Sept. 17, 2015. Health authorities took the the travelers' temperatures and asked about possible contacts with Ebola patients. Travelers were also told to continue monitoring their own temperature and to seek health care if they became ill.  The screening detected 68 travelers with fevers and transported 40 to a medical facility for further treatment, but none had Ebola.

Health experts said the arrival screening proved futile as a measure of protection for public health. At least one person, a New York City doctor who had treated Ebola patients and returned to the United States on Oct. 16, 2014, passed through screening without detection. He monitored his own condition, went to a hospital when he developed symptoms and tested positive for Ebola on Oct. 23. He recovered.

Screening "doesn’t really pick up Ebola,” said Georgetown University law professor Lawrence Gostin, a director of the World Health Organization Collaborating Center on Public Health Law and Human Rights. “When Ebola struck in the United States, there was widespread – I would say irrational – fear and panic. This was a political compromise.”

People from Liberia, Sierra Leone and Guinea underwent screening before they even boarded a plane in those countries. If they showed symptoms, authorities did not allow them to board.

John Wagner, Customs and Border Protection's deputy assistant commissioner for office of field operations, acknowledges it is unlikely that someone would develop symptoms between the time of the exit screening in Africa and their arrival in the United States, but he defends the agency's efforts. The screening helped solidify disease control procedures with the Centers for Disease Control and Prevention and served to educate travelers about monitoring their health. Health authorities collected information at the airport to track down travelers in case they later fell ill, he said.

"I think it went very well overall," Wagner said.

Five U.S. airports to enhance screenings for Ebola

CBP and CDC dropped the screenings Friday for travelers from Liberia after the World Health Organization on Sept. 3 declared the epidemic over.

Feds to end Ebola screening for air travelers from Liberia

Detecting illness in airports is difficult, experts say. Travelers may be asymptomatic or unaware they are sick. Some travelers may lie on questionnaires for fear of quarantine or disruption of their travel plans. And the screenings themselves may be faulty.

Travelers can also get anywhere in the world within a day – faster than a disease incubates to reveal symptoms. Somebody infected with Ebola, which is transmitted through close contact by bodily fluids, could take a week or longer to develop symptoms. Even airborne flu takes two days to incubate from what may have been an unnoticed public exposure.

A February study in eLife, a peer-reviewed online journal, found screenings of  millions of travelers overseas in recent years for influenza and Severe Acute Respiratory Syndrome detected only a couple of dozen cases of flu and none of SARS.

“Many infected travelers will be fundamentally undetectable, even in a perfect world with infallible thermometers and lie-proof questionnaires,” said Katelyn Gostic, lead author of the eLife study and a doctoral student at University of California Los Angeles. “It is just not possible to detect an infected traveler who doesn’t yet show symptoms and doesn’t realize they have been exposed.”

The study projected that “even in the most optimistic scenario, arrival screening will miss the majority of cases.”  That projection, based on studies of a 2009 flu pandemic, assumes a 70% accuracy rate for non-contact thermometers, which resemble guns that point infrared light at the patient's forehead, and travelers answering questionnaires truthfully only 25% of the time.

Of 1.5 million arriving travelers screened for H1N1 flu in Japan, Australia and New Zealand in 2009, screening detected only 22 cases,  the study found. Australia, Singapore and Canada screened 3.1 million travelers in 2003 for SARS and found none, the study found.

The threat of quarantining suspicious travelers discourages people from answering travel and health questions truthfully, medical experts said. A nurse, Kaci Hickox, who arrived in October without a fever after a month in Sierra Leone was quarantined in New Jersey and Maine for the 21-day incubation period for Ebola.

“When you do that, you’re basically creating incentives for people not to be honest with you,” said Ashish Jha, professor of international health and director of the Harvard Global Health Initiative. “As a tool unto itself, it is not that effective.”

Wagner said CBP officers are trained to question people about the purpose and intent of their travel to detect misleading answers, while collecting information to track them and anybody they came into contact with, if necessary.

More important are efforts to train healthcare workers to recognize, treat and possibly isolate dangerously infected patients, Jha of Harvard said.

Doctors treating a patient with fever should ask routinely about travel history and contacts with sick people – not just during an outbreak, he said.

“It’s just a normal part of being a doctor,” he said. “If they say there were in Liberia last week – bingo – now you’ve got something serious to focus on.”

Gostic, the UCLA researcher, compared the problem to fighting wildfires.

“It would be impossible to rid the world of every lightning strike, campfire or discarded cigarette butt, but we also understand that not every spark will start a massive blaze,” she said. “Just like we’d never rely solely on smoke detectors or public service announcements for fire mitigation, we shouldn’t rely on traveler screening to protect us from disease epidemics.”