Although an Ebola outbreak is growing rapidly in central Africa, experts say it doesn’t pose a public health threat to the United States.

The outbreak, centered in the Democratic Republic of the Congo (DRC), has grown to nearly 750 suspected cases and more than 170 deaths, the World Health Organization (WHO) announced today. Although the risk from Ebola in the DRC is high, the risk of global spread is low, WHO Director-General Tedros Adhanom Ghebreyesus, PhD, said. 

Many US infectious diseases experts agree.

Virus is not airborne

“This is a horrible situation in affected areas of Africa,” said Michael T. Osterholm, PhD, MPH, director of the Center for Infectious Disease Research and Policy (CIDRAP) at the University of Minnesota, which publishes CIDRAP News. “But for the world, it is not.”

That’s because Ebola, which spreads through contact with bodily fluids, is far more difficult to spread than the airborne respiratory viruses that Americans have confronted in recent years, such as influenza, COVID-19, measles, and even the Andes strain of the hantavirus, which recently caused an outbreak on a cruise ship.

Two things make Ebola less infectious: how it spreads and when it spreads.

“Ebola is not airborne,” Osterholm said. “There’s no evidence of that at all. To be infected, you’ve got to have body fluid contact with someone who is quite ill.”

Significantly, people with Ebola don’t spread the virus before developing symptoms, said Peter Hotez, MD, PhD, dean of the National School of Tropical Medicine at Baylor College of Medicine. 

Ebola is not airborne. There’s no evidence of that at all. 

And even people with early Ebola symptoms—such as a fever, sore throat, headache and body aches—are unlikely to spread the virus. Ebola doesn’t spread through coughing, sneezing, or shaking hands.

“You cannot get Ebola from passing someone in an airport, sitting near someone freely, or through other casual contacts,” said Captain Satish K. Pillai, MD, MPH, incident manager for Ebola response at the US Centers for Disease Control and Prevention (CDC), said today at a press conference.

Family members, medical providers most at risk

The world learned a lot about how Ebola spreads in 2014, during an outbreak in West Africa that infected more than 28,000 people and killed more than 11,000. It remains by far the world’s largest ever recorded.

A Liberian national named Thomas Eric Duncan traveled from Liberia to Dallas, Texas, where he became sick and eventually was diagnosed as having Ebola. Although Duncan shared a small apartment with his family in the days before he was hospitalized, none of them developed Ebola. 

People with Ebola are most contagious after the disease becomes advanced, when viral levels climb and lead to symptoms such as diarrhea, vomiting, and bleeding, Hotez said. 

“It’s likely the risk increases exponentially as the disease progresses,” Hotez said.

In the advanced stage of the disease, people are typically hospitalized and too weak to walk around or spread the virus in public places, Hotez said. In communities without hospitals, people with advanced Ebola tend to be bedridden at home.

The people most at risk of contracting Ebola are family members or medical professionals caring for infected patients, because they may come into contact with the sick person’s blood, vomit, or diarrhea. Craig Spencer, MD, MPH, an emergency medicine physician who came down with Ebola after treating patients in West Africa in 2014, describes Ebola as a “disease of compassion,” because the people at greatest risk are those whose love or professional dedication exposes them to the bodily fluids of very sick people.

“By the time you’re sick in the ICU [intensive care unit], that’s when you are maximally contagious,” Hotez said. 

The only people that Duncan infected while in Dallas were two hospital nurses who took care of him when he was critically ill, Osterholm said. The nurses weren’t adequately shielded with personal protective equipment.

By the time you’re sick in the ICU, that’s when you are maximally contagious.

In some African countries, people traditionally touch or wash the bodies of the deceased to prepare them for burial. That’s extremely risky, because dead bodies can continue to spread the virus, Hotez said.

“A recently deceased Ebola patient is a sack of virus,” Hotez said. “It’s why relatives who bury their loved ones also get sick.”

Outbreaks can be avoided

Many Americans in 2014 were critical of Spencer, because he didn’t quarantine after returning from West Africa. But Spencer did the right thing by monitoring his temperature twice a day and immediately seeking medical care when he developed symptoms, Osterholm said.

The hospital where Spencer was admitted, Bellevue Hospital in New York City, had prepared to handle patients with Ebola, and no one was infected.

Spencer’s experience shows that people returning from countries with Ebola outbreaks can avoid infecting others without being locked inside, Osterholm said.

Passengers who return to the United States after visiting the DRC or Uganda should be instructed to monitor their health for any signs of illness and be told how to immediately contact public health officials, Osterholm added. The incubation period—the time from exposure to first symptoms—for Ebola is two to 21 days.

Travel bans ‘don’t make sense’

In spite of the minimal risk to travelers, the Trump administration issued new travel restrictions yesterday for US citizens and permanent residents who have been in the DRC, Uganda, and South Sudan. Uganda has had a handful of Ebola cases, while South Sudan has had no cases but borders the two countries.

For the next 30 days, passengers who have visited these countries in the past three weeks now must fly through Washington-Dulles International airport in Virginia, where they will be screened for Ebola.

Non-citizens who have recently visited these countries are banned from entering the country. The travel ban forced a flight to Detroit to be diverted to Canada this week because a traveler from the DRC was on board.

Politicians often want to take an action, and this blunt action [travel bans] makes it appear that they are.

Travel bans don’t make sense scientifically, said Amesh Adalja, MD, a senior scholar at the Johns Hopkins Center for Health Security.

Travel bans “are a favorite tool of politicians,” Adalja said. “Politicians often want to take an action, and this blunt action makes it appear that they are.”

Yet travel bans actually “make things worse by making it logistically more difficult to get resources to the outbreak zone,” Adalja said.