How The U.S. Will Contain The Spread Of Ebola: Good Old Legwork

Contact tracing is the key to preventing an epidemic.

The U.S. Centers for Disease Control and Prevention announced yesterday that a patient with Ebola has been identified in the U.S. He apparently got infected while in West Africa, boarded a plane before he had any symptoms, and then visited a U.S. hospital when he fell ill. He’s now getting care at a hospital in Dallas.

If you’re one of the 300-plus million people who live in the United States, there’s a non-zero—if vanishingly small—chance you may have been infected by this person. How can you know for sure? Well, you’ll get a knock on your door from somebody called a tracer.

The tracer will be part of the major technique with which U.S. officials plan to keep Ebola from spreading in America. The technique is called contact tracing. It’s a generations-old idea, it’s pretty unglamorous, but it works. “There is no doubt in my mind that we will stop it here,” U.S. Centers for Disease Control and Prevention Director Thomas Frieden told reporters yesterday during a conference call. Experts outside of the CDC agree. Contact tracing has also appeared to have helped control outbreaks in Nigeria and Senegal. Unfortunately, other challenges keep it from working perfectly in Guinea, Liberia, and Sierra Leone, where Ebola is an epidemic.

Here’s how contact tracing works—and what to expect if, one day, you find yourself getting traced.

What is contact tracing?

Doctors caring for the Dallas patient will (or already have) speak to everyone with whom he had direct contact while he had the symptoms of Ebola, but wasn’t yet staying in a hospital isolation room. In this case, four days passed between when the patient first developed symptoms and when doctors placed him in isolation. Anyone who might have contacted the patient’s bodily fluids during that time is at risk for having contracted Ebola. Dallas officials think 12 to 18 people are at risk.

Tracers must track down and visit each of these direct contacts, every day, for 21 days. Twenty-one days is the longest possible time that somebody could harbor Ebolavirus, but not show symptoms. “By then, if they’re not sick with Ebola, they’re not going to get sick with Ebola,” Daniel Bausch, a physician and researcher who studies infectious diseases at Tulane University, tells Popular Science. Those who stay in the clear for 21 days are off the contact list.

During their visits, tracers ask the traced people how they’re feeling. Tracers may ask the traced contacts to take their temperature every day and record it. Tracers, who are often recruited from the community, don’t need any special medical training. They submit their findings to trained epidemiologists, who decide what to do next.

What happens if a traced contact gets sick?

If the traced person reports having a fever or headache—the early symptoms of Ebola—he or she will be isolated. She might not have to go to the hospital right away, especially if her living situation is pretty isolated already. (Think “my own house” versus “dorm.”) After all, she might not have Ebola. Plenty of diseases, such as colds and flus, also cause fever and headache.

Officials may ask the headachy contact to simply stay in her house or bedroom while they test her blood for Ebola. If she tests positive, then they’ll take her to an isolation unit in a nearby hospital.

Officials will also then have to start the whole contact tracing process all over again for all of the new case’s contacts.

Who counts as a traceable contact?

Family who housed the original Dallas patient during his four infectious days definitely count. Briefer contacts, such as store clerks, probably don’t, unless there’s reason to believe those people touched the patient’s bodily fluids, Bausch says.

The patient entered the U.S. on a commercial flight, but U.S. health officials will not be calling folks who shared his flight, Frieden says. The patient did not have symptoms during the flight, and people with Ebola can’t transmit the virus while they don’t have symptoms.


Why should a traced person cooperate with the authorities?

Not all traced people do. They could leave the house when they’ve been told not to. They could go stay in another city without telling their tracer. Or they may wish to cooperate, but may be difficult to find, for example, if they don’t have a fixed address.

In this case, people should have one good motivation to cooperate, Bausch says. If they are infected and are traced, they can get swift treatment. While there’s no cure for Ebola, those who are infected can get “supportive treatment,” such as a hydrating IV, to help them recover. Supportive treatments aren’t considered cures because they don’t kill Ebolavirus, but they boost the chances that the body’s immune system will.

There are also some experimental Ebola-killing drugs available. It’s not clear how widely available those would be if more people in the U.S. get sick with Ebola, but Frieden says officials are discussing experimental treatments with the Dallas patient’s family and hospital.

Has the U.S. ever used contact tracing before?

U.S. health authorities have previously traced the contacts of people with tuberculosis and with Middle East Respiratory Syndrome, or MERS.

Contact tracing around the world was instrumental in eradicating smallpox.

In the future, if some kind of deadly swine or avian flu lands in the U.S.—expect contact tracing.

Why will it work here, but not in countries where Ebola is an epidemic?

Authorities are trying to conduct contact tracing in Guinea, Liberia, and Sierra Leone, but it’s harder there. Contact tracing is labor-intensive, and there are many more people infected in West Africa. The U.S. has only one infection so far. Many West African residents are also harder to reach than the average American. They may live hours away, in rough country, or they may live in slums with no set address. They may also not want to cooperate with tracers, out of fear and suspicion of healthcare workers. CNN reported on the challenges of contact tracing in West Africa last month.

Experts are confident contact tracing will work as expected in the U.S. The U.S. has plenty of resources to track all those people and Americans are likely to cooperate with tracers.

Could Ebola land in the U.S. again?

It could. Airports operating flights between Ebola-endemic countries and the U.S. screen travelers before they fly. However, as Frieden explained, “As long as there continue to be cases in West Africa, the reality is that patients travel, individuals travel, and as appeared to happen in this case, individuals may travel before they appear to have any symptoms.”

If the disease lands again, this whole contact tracing thing will start all over.