This week we asked Dr. Richard Besser, ABC's chief health and medical editor and the former acting head of the CDC, to answer five simple questions about the Ebola outbreak in Africa and the Americans affected by the virus. Besser joins "This Week" tomorrow for the latest on the Ebola outbreak.

1) So, many Americans have probably heard of Ebola, but what exactly is it and how does someone get it?

Besser: Ebola is an infectious disease caused by a virus. It belongs to a group of diseases called hemorrhagic fevers. It occurs primarily in remote villages in Central and West Africa, near tropical rainforests. The virus is transmitted to people from wild animals and spreads in the human population through human-to-human contact (NOT through the air). That transmission only happens with close contact with the fluids of infected people or animals: vomit, blood, urine or diarrhea. It can also come from contact with infected instruments - for instance, getting an injection with a needle that has picked up the virus, or from a surface where infected fluids have been. This means it spreads among families taking care of an Ebola patient, and among medical workers taking care of them. The virus can spread in burial rituals - if people touch and wash an Ebola sufferer who has those fluids on their bodies.

WATCH: Full ABC News coverage on the Ebola outbreak

2) Generally, how deadly is Ebola and how is it treated?

Besser: There's no vaccine against it, and no treatment that cures it. Depending on the outbreak, between 50 percent and 90 percent of the people who get it can die. In the current outbreak in West Africa, about 60 percent of the patients who have gotten it have died. In other words, in some outbreaks, up to 90 percent of people who get Ebola die from the disease. When someone gets Ebola, they may lose a lot of fluids (from vomiting and diarrhea), so the treatment given them is mostly to replace those fluids (IV saline), monitor their blood pressure, and give them pain relievers to keep them as comfortable as possible. They call this "supportive care." The best way to "treat" Ebola is to prevent it, by quarantining anyone who may have had that close contact with the fluids of an Ebola patient until they're sure they don't have the virus (that's about three weeks, since the incubation period is between three and 21 days). Health care workers working with Ebola must have every inch of their bodies covered at all times, to keep them from being contaminated with fluids that hold the virus. Every time they leave the Ebola isolation ward, they are sprayed down with disinfectant as they shed their protective layers.

Ebola: What You Need to Know About the Deadly Outbreak

3) Where is this Ebola outbreak and why is it different from other outbreaks? How bad is this specific situation?

Besser: This is the worst recorded Ebola outbreak in history (since the disease was identified in the 1970's), with 1,323 cases and 729 deaths as of July 27. CDC Director Tom Frieden has called this outbreak "the biggest, the most complex, and the first time it's been present in this region." The epicenter of the outbreak is the shared border between Sierra Leone, Guinea and Liberia, and part of the reason it has spread so widely is that that border area contains cities - it's harder to identify the people who've come in contact with an Ebola patient and isolate them when the population is larger. An infected Liberian/American whose sister had died from Ebola recently traveled by plane from Liberia to Nigeria and then died there, and several people who had direct contact with this man are now being quarantined. The outbreak virus seems genetically similar to an outbreak strain reported in 2009 in the Democratic Republic of Congo.

Continuing Coverage of the Ebola Outbreak from ABC News

4) Bottom line, do Americans not traveling abroad have to be worried? An American with Ebola is being treated in Atlanta, right?

Besser: One American with Ebola is receiving treatment at a special isolation unit at Emory in Atlanta now and another will be coming. They were working as medical missionaries in an Ebola treatment center in Liberia when they began having symptoms. The American isolation units that they are being treated were set up in collaboration with the CDC for patients with serious infectious diseases. According to CDC director Frieden: "It is physically separate from other patient areas and has unique equipment and infrastructure that provide an extraordinarily high level of clinical isolation. It is one of only four such facilities in the country." Americans who are not traveling abroad have little reason for concern. Here in the U.S., most hospitals have the capacity to isolate patients, plus Ebola can only be spread through direct contact with bodily fluids. If you are not in close contact with someone who is sick who has just returned from West Africa, who in turn was in close contact with the body fluids of an Ebola patient, you have little reason for concern.

What Happens Once Ebola Patients Arrive in the US? Here's the Plan

5) What about Americans traveling abroad? What do they need to know?

Besser: The CDC issued a travel advisory against "non-essential travel" to the hardest hit countries: Guinea, Sierra Leone, and Liberia. The Peace Corps announced Wednesday its more than 340 volunteers are being removed from the same countries (Guinea, Sierra Leone, and Liberia) due to the increasing spread of the virus. It's inadvisable to travel to these West African countries right now, and neighboring countries may also be affected.

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