Why Airport Screening Won't Stop Ebola, The Economist Explains

Originally posted at The Economist,

Those who got sick, and there were many, developed large, dark blisters that oozed pus and blood. Later came fever and bloody vomiting. Long before Ebola, there was the Black Death, which killed millions in the 14th century. And as with Ebola, nervous officials tried to keep the sick from entering their cities. Venetian authorities held ships at bay for 40 days—hence the word quarantine—to check for infections. Still, the disease ravaged the republic. Today countries are screening air passengers arriving from the places affected by Ebola. Will these efforts prove more effective?

 

 

Ebola has killed more than 4,000 people, nearly all of them in west Africa. But the threat to countries outside the region became clear when a Liberian man, Thomas Duncan, was diagnosed with the disease in America. He probably contracted it while helping an infected woman in Liberia. He then hopped on a plane to America. Mr Duncan died in Dallas on October 8th, the same day American officials announced that travellers from the countries hardest hit by Ebola—Guinea, Liberia and Sierra Leone—would be questioned about their health, travel and contact with the sick, and have their temperatures taken at five large airports. Quarantine is an option for those suspected of being ill. A day later Britain announced that it would screen travellers from these countries at Heathrow and Gatwick airports (and two rail terminals). African and Asian countries have been screening air passengers for months, with some using infrared cameras to detect fevers. This is in addition to the screening of all departing air travellers in the affected countries.

Some governments are dusting off measures that were previously used to combat the spread of bird flu and the Severe Acute Respiratory Syndrome (SARS). But David Heymann, a professor at the London School of Hygiene and Tropical Medicine, says screening did not stop those diseases and it is unlikely to stop Ebola. Consider Mr Duncan, who did not have a fever when leaving Liberia, nor when landing in America. He only developed symptoms a week later. American officials admit that the new screening procedures would not have caught him. It can take up to 21 days for someone to show signs of Ebola. Passengers who wish to avoid quarantine, especially in African Ebola wards, or receive treatment in the West, may also lie. Mr Duncan did not tell Liberian officials that he had been in contact with the sick.

During the SARS outbreak, some air passengers took painkillers to reduce their temperatures. Others may not know that they are infected, and infrared scanners are not always reliable. "I would expect a handful of cases in the next few months," warned Sally Davies, Britain's chief medical officer, after the screening measures were announced.

 


Screening may at least calm people down, however. Notwithstanding the bungled effort to diagnose and treat Mr Duncan in Texas, where a health-care worker has also tested positive for the disease, developed countries are well-equipped to contain Ebola. The announcement of screening has focused minds. It is also a measured response—not as economically painful as a full travel ban, or as inconvenient as mass screening. But the best way to stop Ebola from spreading, say health experts, is to drain the reservoir of the disease, which means tackling it in west Africa. Doing that presents an entirely different set of challenges. When it comes to stopping Ebola, the rich world's self-interest aligns neatly with the needs of the developing world. But countries in a position to help have been slow to act.