Ebola in the U.S.: What you need to know now

The Centers for Disease Control and Prevention confirmed Tuesday that a patient in the U.S. has been diagnosed with the Ebola virus. Amid fear that the virus has arrived on our shores, many are asking questions about the disease and how it is transmitted.

Here's what you need to know about Ebola. The information comes from the World Health Organization and the U.S. Centers for Disease Control and Prevention.

How did Ebola get to the U.S.?

The patient diagnosed with Ebola at a Dallas hospital had recently traveled by plane from Liberia to the U.S. to visit family, the CDC said. He landed in the U.S. on Sept. 20 and began exhibiting symptoms of the virus four days later.

What do we know about the patient?

The man was identified Wednesday as Thomas Eric Duncan, a Liberian national, CBS station KTVT reports. Officials did not release any personal details about him or how he may have become infected in West Africa. They said he is critically ill and has been in medical isolation at Texas Health Presbyterian Hospital in Dallas since Sunday.

Are other passengers at risk?

"There is zero risk of transmission on the flight," said CDC director Dr. Tom Frieden. "Ebola doesn't spread before someone gets sick, and he didn't get sick until four days after he got off the airplane. So we don't believe there was any risk to anyone on the flight." Frieden declined to release any details about the man's itinerary or flight numbers.

What about other people in Texas?

Public health officials say they are actively tracing everyone who's been in close contact with the man since he started developing symptoms and became contagious. Those people will be monitored for 21 days, the length of the disease's incubation period, and if they develop a fever they'll be put into medical isolation.

Health officials could not rule out the possibility that other people might have been exposed. "While it is not impossible that there could be additional cases associated with this patient in the coming weeks, I have no doubt that we will contain this," Frieden said.

How is Ebola spread from person to person?

The good news is that Ebola isn't transmitted through the air. You aren't going to get Ebola if an infected person sits next to you or sneezes in the same room. The disease is transmitted through direct contact with bodily fluids, such as blood from an infected person. The disease is only contagious when an infected person is showing symptoms.

Health care workers are particularly at risk if they are not wearing appropriate protective equipment, such as masks, gowns and gloves.

What are the symptoms of Ebola?

Ebola is a hemorrhagic virus characterized by the sudden onset of flu-like symptoms including fever, intense weakness, muscle pain, headache and sore throat. These are followed by vomiting, diarrhea, rash, impaired kidney and liver function, and sometimes internal and external bleeding.

Just how deadly is Ebola?

Somewhere between 50 percent and 90 percent of the people who develop Ebola will die.

What's the incubation period for Ebola?

The time from infection with the virus to the onset of symptoms ranges from two to 21 days.

Is there a cure for Ebola?

Right now, there is no cure or vaccine. Doctors typically provide supportive care to patients, which may include oxygen, fluids, blood transfusions and treating subsequent infections. A few patients infected with the virus have been given experimental treatments, including doses of a promising drug called ZMapp. But supplies of ZMapp were limited and have since run out.

Several patients also appear to have been helped by blood transfusions from a person who survived Ebola and developed antibodies to the virus.

At the beginning of September, the National Institutes of Health began a clinical trial on a potential vaccine for the virus, but it is not being used on patients.

How bad is the outbreak in West Africa?

As of Sept. 28, 2014, there have been 7,178 cases and 3,338 deaths from the virus during the current outbreak in West Africa, according to the World Health Organization. Almost all of the cases have occurred in the nations of Guinea, Sierra Leone and Liberia.

This is by far the largest and deadliest outbreak of Ebola since the disease was first identified in 1976. More people have died in the last six months than in all other Ebola outbreaks combined. The CDC says as many as 1.4 million people could be infected by January unless more is done to stop it.

Why has it been so hard to contain the outbreak in West Africa?

A big part of the problem in West Africa is that the health care infrastructure is poor, understaffed and ill-equipped to deal with a major public health crisis. There's also widespread mistrust of hospitals and doctors that keeps many people from seeking treatment. The high death rates at hospitals have many people so scared that they keep ailing loved ones at home, where they continue to spread the disease to others.

"There's all the difference in the world between the U.S. and parts of Africa where Ebola is spreading," Frieden said. "The United States has a strong health care system and public health professionals who will make sure this case does not threaten our communities."

What's the history of Ebola?

Ebola first appeared in 1976. There were two simultaneous outbreaks, in Nzara, Sudan, and in Yambuku in what is now the Democratic Republic of Congo (formerly Zaire). The Congolese outbreak occurred in a village near the Ebola River, which is how the disease gets its name.

Fruit bats in the African forest are thought to be the natural host of the virus. In Africa, people have become infected through the handling of infected fruit bats, chimpanzees, gorillas, monkeys, forest antelope and porcupines found ill or dead or in the wild.