With officials confirming the first Ebola case diagnosed in the United States, and the first case diagnosed outside of Africa during this outbreak, some Americans continue to express fear that the deadly disease -- which is believed to have killed at least 3,091 people in West Africa -- could spread in the United States.

If you're one of them, you can calm down. Health officials say there is virtually no danger to the public. Here’s what you need to know about the virus:

What’s the likelihood of a major Ebola outbreak happening in the U.S.?

Remote, according to officials from the U.S. Centers for Disease Control and Prevention. Now that an Ebola patient has been diagnosed in Texas, the first human case ever diagnosed in the United States, health officials say the American health system will work to contain the disease and the likelihood of it spreading is very low.

Once an Ebola patient is identified here, says CDC Director Thomas Frieden, protocols allow doctors and health officials to quickly isolate and treat the person, and to put anyone who may have come in contact with him or her under close surveillance for 21 days, the incubation period for Ebola.

If any of those people develop symptoms, the contact tracing cycle begins all over again.

The CDC has issued travel advisories recommending that U.S. citizens avoid nonessential travel to the most affected countries, but have also said Ebola exit screening at airports in West Africa and entry screening for those travelers arriving from affected countries will identify anyone showing symptoms of the virus.

The CDC has said in the past that it’s very unlikely that American travelers to West Africa could contract the disease, since they’d have to come in direct contact with an infected person’s blood, organs or other bodily secretions, but it issued the advisories amid concerns that travelers might find themselves at risk in West African hospitals.

Weak healthcare systems in West Africa have led to the virus spreading rapidly there. So have traditional burial rituals that involve washing the bodies of loved ones after death.

Why are we allowing people with Ebola into the country?

The patient who was diagnosed at a Texas hospital on Sept. 30 was not showing any symptoms of the disease until four days after arriving in the U.S., CDC and hospital officials said.

The person was subject to screening when leaving West Africa and upon arrival in the United States and exhibited no symptoms of the disease at the time, officials say. That means the patient was not contagious at the time, and there was no reason to isolate the person or restrict his or her movement into the United States.

In the case of three U.S. missionaries who were evacuated to American hospitals after becoming ill with Ebola, officials have said bringing them to the U.S. ensured that they had access to “modern medical facilities and technology” that could save their lives.

Dr. Kent Brantly, missionary Nancy Writebol and Dr. Rick Sacra all contracted Ebola while working in West Africa and were evacuated to the United States for treatment.

They have all since recovered and been released.

No other secondary infections have been reported as a result of their transport and treatment here.

Were other people in the plane or at the airport with the patient in danger?

CDC officials have not revealed the flight on which the Texas patient arrived to the United States, saying there was “zero risk” of transmission to anyone traveling with the person since he or she did not show symptoms until four days after arriving.

The CDC says there’s no reason to think anyone on the flight might have been at risk.

The patients who have been evacuated to the United States have been transported via specially equipped medical planes outfitted with an isolation pod, a portable, tent-like structure that can prevent infected patients from exposing flight crews and other personnel.