The more that Ebola makes headlines, the more it sows confusion.

Many Americans are asking basic questions about the virus, like whether they can get it from a doorknob or a pet or from riding a plane.

The sense of confusion has been fed by a shifting response to the Ebola outbreak in the United States on the part of the government and officials. After resisting calls for the appointment of an "Ebola czar," President Obama named one on Friday. And after saying the disease would be stopped in its tracks in the U.S., Thomas Frieden, head of the Centers for Disease Control and Prevention, said the agency would "rethink" its infection control procedures now that two nurses have contracted the disease.

Some schools have been closed in Texas and Ohio on fears that students, staff, or their friends or relatives, might have been exposed to the virus on recent flights shared with one of the Dallas nurses who is now infected, Amber Vinson. The CDC is looking to talk to more passengers who flew with Vinson. And sales of hand sanitizers are rising.

View Images A custodial worker cleans the inside of Davis Elementary School in Garland, Texas. The school remains closed after it was discovered that parents of a Davis student were on the same flight as the second Texas Health Presbyterian Hospital nurse who tested positive for the Ebola virus earlier this week. Photograph by Chip Somodevilla, Getty Images

The virus has killed about 4,500 people in Guinea, Liberia, and Sierra Leone, but so far only one person has died in the United States (and he contracted it in Liberia).

In an attempt to separate fact from fiction, here are answers to questions about the Ebola virus surfacing in the news this week.

If I flew on the plane that the infected nurse traveled on, should I worry?

The CDC originally wanted to interview only people who were on Frontier Airlines flight 1143 from Cleveland to Dallas/Fort Worth on Monday, October 13. That's the flight that Vinson was on the day before she entered the hospital.

But on Thursday the CDC said that it also wants to hear from passengers on Frontier Airlines flight 1142, from Dallas/Fort Worth to Cleveland, on Friday, October. 10, which Vinson took a few days earlier. Anyone on either of those flights should call 1-800-CDC-INFO.

CDC officials are concerned that Vinson may have been ill earlier than originally thought. So they've expanded their investigation to the earlier flight. But because of how the virus is transmitted, Vinson would have had to have been symptomatic and passengers would have needed to have direct contact with her bodily fluids to be at risk for infection. Just being on the same plane with her would not be enough.

The Frontier crew says Vinson showed no visible signs of infection when she flew on Monday. But it cleaned the plane several times, going above and beyond CDC guidelines. The plane has temporarily been taken out of service.

I'm just a normal person, not a health care worker. What should I be doing to stay safe?

For one, don't panic. So far the only people to contract the infection in the U.S. are the two nurses who were treating Thomas Duncan, the Ebola patient who died in Dallas last week. Wash your hands or use alcohol-based hand sanitizer-not necessarily because Ebola is a threat, but to prevent far more common infections, like norovirus, the common cold, or influenza. The annual flu shot, now available, can also help stave off that disease. And because some symptoms of flu and Ebola overlap, avoiding the flu can cut down on "Do I have Ebola?" panic.

Don't take supplements that claim to prevent or treat Ebola. The trade group representing supplement makers said there's no evidence to show they work, and the Food and Drug Administration has already sent warning letters to some manufacturers making that claim.

View Images NG Staff. Sources: Gerardo Chowell, Arizona State University; WHO; CDC

Can hand sanitizer protect from Ebola?

Health care workers in contact with Ebola patients cannot rely on sanitizer or soap and water alone. That's why they're using protective gear. For members of the general public who are not in contact with anyone known to be infected, the CDC and World Health Organization say soap and water or alcohol-based sanitizer are good general hand hygiene precautions. (Use soap and water if your hands are visibly dirty.) That will help you be protected from a host of communicable diseases.

Wouldn't a ban on traveling by people from West Africa keep Americans safe?

The Centers for Disease Control and Prevention has consistently said that a travel ban would only isolate the countries where the epidemic is raging and might even affect the flow of aid workers and supplies. President Obama backed up this view, while the Federal Aviation Administration has said the government will consider the situation day by day.

Some members of Congress are pushing for a ban, however, and a public health expert told National Geographic last week that there are sound arguments to be made both for and against. An early ban would have prevented Duncan from entering the U.S., after all.

View Images An emergency medical service employee from Roissy-Charles-de-Gaulle airport in France uses an electronic thermometer to conduct a health check on a passenger arriving from Guinea. Photograph by Kenzo Tribouillard, AFP, Getty Images

How does this outbreak compare to other epidemics?

This is by far the largest outbreak of Ebola. The first outbreak of the disease in 1976 included 318 cases; the biggest outbreak before this one was in 2000-2001, with 425 cases and 224 deaths. (That virus was a different species than the one implicated in this outbreak.) But in terms of other infectious diseases, this outbreak is tiny. The Spanish Flu of 1918-19 is estimated to have killed from 30 million to 50 million people. The CDC estimates that almost 12,500 people died in the U.S. alone from the H1N1 flu pandemic in 2009-10.

When do Ebola patients become contagious?

Ebola is not like the flu; it can't be spread by people who have been infected but are not yet showing symptoms, says Amy Ray, an infectious disease specialist and chairperson of the University Hospitals System Infection Control Committee in Cleveland, Ohio. So the CDC says that until they have a fever greater than 101.5 degrees, along with other symptoms of the disease-including body aches, diarrhea, and vomiting, they cannot spread the virus to others.

Can I catch Ebola if a patient with the disease sneezes on me?

Unlike flu, Ebola doesn't invade the airways, says Ray. Transmission is usually through bodily fluids like blood, vomit, and feces. That said, if the patient is sick enough, some of the virus will be present in the saliva. And while the virus itself doesn't make patients sneeze or cough more than usual, if they do so and another person is in range, saliva or mucus droplets can enter the eyes, nose, mouth, or broken skin. So yes, says the CDC, it's theoretically possible.

But you'd have to be up close and personal with someone who was quite ill already. That could be a problem for health care workers or for family members of infected patients. It's not likely to be a problem for the general public.

Can I catch Ebola by using a doorknob that a symptomatic patient sneezed on?

The virus can live for a few hours on hard surfaces, the CDC says. Ray says the exact survival time has not been very well studied. At a recent meeting on infectious disease, a physician from Emory University, which has treated some of the U.S. patients who contracted Ebola in West Africa, reported that personnel swabbed the rooms of infected patients and found no viral RNA. They did, however, find it in the patients' bodily fluids. Contact with those is the bigger worry.

Can dogs and other pets contract and spread Ebola?

Pets are not believed to be a significant risk in the U.S., the CDC says. Wild animals, including bats and monkeys, can become infected. Among domestic animals, dogs and pigs can contract the virus, though dogs don't seem to actually get sick from it. Could a pet dog transmit the virus to humans? There are no reports of this happening so far, but as a precaution, the dog of the first nurse who was infected in the U.S. is being quarantined.

Can the virus mutate to become airborne?