The Ebola virus now striking Zaire is deadly, but its spread can be controlled because it kills its victims far more quickly and easily than it spreads to new ones.

Most scientists believe that the three known strains of human Ebola spread from one person to another through contact with bodily fluids -- primarily blood -- and not through air, water or casual contact.

"I've been inside huts, surrounded by people who were dying of this disease, where there was no air exchange at all, and I've never gotten Ebola," said Dr. Joseph McCormick, the only scientist who has witnessed all three human outbreaks of the virus.

Unlike the scientists depicted in the movie "Outbreak," who examined patients while wearing full body respirator "space suits," McCormick's protection has been simple: a surgical mask, eyeglasses, a surgical cotton gown and two layers of latex gloves.

"That's enough," McCormick says. "And it's just silly to talk about wearing a mask while walking down the street. This virus isn't going to fly into your face."

As a result, the spread of Ebola can be controlled through relatively simple means, such as disinfecting medical equipment and not touching or shaking hands with anyone who may be infected in case they have bodily fluids on their skin.

"We must wash our hands with soap before we eat, avoid other people's blood and body fluids," Vincent Mapuko, a businessman in Kinshasa, told the Associated Press. "As soon as we have symptoms, we must go to the hospital."

Once people are infected, they usually get sick quickly - within an average of seven to 10 days, although symptoms, which include headaches, bloody diarrhea and fever, can occur as early two days from infection.

In addition, the disease is easiest to spread when patients are at their sickest and the virus begins to destroy the linings of blood vessels and capillaries, and blood oozes from every opening on the body.

"We are, in a sense, fortunate that this is a remote and fairly poor area," said Ruth Berkelman, an expert on emerging diseases for the Centers for Disease Control and Prevention. "It's unlikely these people will be moving around, particularly outside the country."

But unlike previous outbreaks, this one occurred in a large city, not a small village, creating a greater chance that it will spread outside the immediate area.

Ebola outbreaks have been identified only three times before -- in Yambuku, Zaire in 1976, and in Nzara, Sudan, in 1976 and 1979 -- where up to 90 percent of those who were infected died. There is no vaccine for Ebola and no treatment.

Because of its scanty history, the virus remains mysterious in many ways. It's not known, for instance, what animal or insect may carry it and where it hides in between outbreaks.

Some scientists also suspect the virus might be transmitted by air in unusual circumstances. When a monkey form of Ebola broke out in an animal facility in Reston, Va., in 1989, some monkeys seem to have become infected that way. Fortunately, that strain, dubbed Ebola Reston, was not capable of causing disease in human beings.

Nevertheless, McCormick and other scientists who have witnessed these epidemics are convinced the virus primarily spreads in the following ways:

Needles. As in the current case, hospitals fostered the outbreaks by spreading it, primarily through reuse of contaminated syringes. McCormick said it is likely that isolated cases of Ebola happen frequently, but go unnoticed until hospital practices spread it quickly.

Surgery. Wherever sterile techniques are ignored, there is the danger of Ebola transmission from patient to health provider, and vice-versa.

Sexual intercourse. Spouses of Ebola carriers -- individuals who were unknowingly infected and incubating the virus were infected, presumably through blood passage during intercourse.

Funerary rites. In Nzara, the Sudanese village that has seen two outbreaks, women are exposed to blood and other fluids of the dead when they prepare bodies for burial.