Here’s what you need to know about Ebola in the US

With the first confirmed U.S. Ebola case come fears of an outbreak, health officials have been working to calm the fears of those worried about an epidemic on the scale of that currently faced in West Africa. Here’s what you need to know:

What’s going on?

The CDC confirmed on Tuesday that the first U.S. Ebola patient had been diagnosed at a Dallas hospital. Health officials had been warning for months that someone could unknowingly carry the virus into the country.

The patient was reported on Thursday to have come in contact with up to 80 people, including five children, between returning to the U.S. and being placed in isolation. They’re being monitored for symptoms, and some of the man’s family members have been ordered to stay home until at least Oct. 19 to avoid possibly spreading the disease. Health officials have a list of 100 people who may have had contact with the patient, but only “a handful” of those were possibly exposed to Ebola.

There have also been reports that the man was seen throwing up outside of his apartment before being hospitalized, a concern because Ebola spreads through contact with an infected person’s body fluids.

On Wednesday, a person in Hawaii was placed in isolation over Ebola concerns, but the diagnosis was ruled out on Thursday. The hospital told ABC News the patient could have had any number of things, but officials were just being cautious.

What, exactly, is Ebola?

The Ebola virus disease first appeared in 1976 in Sudan and the Democratic Republic of the Congo. The virus takes its name from the Ebola River, near the village where one of the outbreaks occurred.

The virus spreads from infected wild animals to humans (and from human to human) through close contact with infected bodily fluids. Ebola can’t spread through the air and humans aren’t contagious until they start exhibiting symptoms.

Early symptoms include fever, fatigue, muscle pain, headache and sore throat, according the World Health Organization, followed by vomiting, diarrhea, rash, symptoms of impaired kidney and liver function, and occasionally internal and external bleeding.

How did this happen?

The Dallas Ebola patient was exposed to the virus in Liberia, where he helped transport a pregnant woman with Ebola to the hospital. The woman was turned away for lack of space, and he helped her home, where she later died, according to The New York Times.

He traveled from Liberia to Belgium on Sept. 19, then on to Dulles International and Dallas-Fort Worth. It wasn’t until Sept. 24 that he started exhibiting symptoms.

He told an emergency room nurse that he had traveled from Africa, but word wasn’t passed along to the rest of the hospital and he was released. A few days later, the patient returned to the emergency room in an ambulance, was put in isolation and eventually tested positive for the virus.

Ebola has sickened at least 7,100 people in West Africa and killed more than 3,300, according to WHO. Liberia has been hit particularly hard, along with Guinea and Sierra Leone.

What happens next?

Despite the Dallas diagnosis, the chance of a U.S. outbreak is extremely low, according to health officials. So far, outbreaks have been in poor regions without adequate healthcare, and U.S. hospitals and laws are better suited to dealing with cases of the disease.

Those believed to have had close contact with the Dallas patient will be monitored for symptoms through the 21-day incubation period, as will be anyone else appearing to show symptoms of the disease.

U.S. healthcare workers have been instructed to screen patients for signs of Ebola and to question them about their travel history. Officials carefully track anyone who may have been exposed to the virus and are on high alert after the breakdown in communication in Dallas.

Production efforts are being ramped up for an experimental drug, ZMapp, which officials are calling a “promising” treatment.