(CNN) — As the worst Ebola outbreak in history touches the United States with the diagnosis of the first case within America, questions arise about how the infectious virus is spread.
Ebola is spread by someone who is ill and showing symptoms of the virus. As people with the virus become sicker, they become more infectious, experts say.
“Remember, Ebola doesn’t spread before someone gets sick,” Dr. Thomas Frieden, director of the Centers for Disease Control and Prevention, said Tuesday. “Ebola does not spread from someone who’s not infectious. It does not spread from someone who doesn’t have fever and other symptoms.
“So, it’s only someone who’s sick with Ebola who can spread the disease,” Frieden said.
The transmission of the virus occurs through contact with bodily fluids — such as blood, sweat and feces — from infected humans or animals.
According to the CDC’s website, “Health care providers caring for Ebola patients and the family and friends in close contact with Ebola patients are at the highest risk of getting sick because they may come in contact with infected blood or body fluids of sick patients.”
The virus cannot travel through the air, like a cold or flu virus.
“This is not an airborne transmission,” said Dr. Marty Cetron, director of CDC’s Division of Global Migration and Quarantine. “There needs to be direct contact frequently with body fluids or blood.”
Although a transmission could occur when someone shakes the sweaty hand of an infectious person — the uninfected person would have to have a break in the skin of their hand that would allow entry of the virus, said CNN’s Dr. Sanjay Gupta.
“Keep in mind, this is something that’s spread through bodily fluids,” Gupta said. “Once somebody starts to get sick, it means the virus is being excreted in their bodily fluids. Shake hands with somebody … and you think I don’t have breaks in my skin, (but) we all have minor breaks in our skin. And there is a possibility that some of the virus can be transmitted that way.”
Medecins Sans Frontieres says that while the virus is believed to be able to survive for some days in liquid outside an infected organism, agents such as chlorine, heat, direct sunlight, soaps and detergents can kill it.
What about planes? Can fellow passengers become infected if someone on the flight has the virus? Could Ebola spread around the world via air travel?
While the CDC acknowledges it is possible a person infected with Ebola in West Africa could get on a plane and arrive in another country — which is apparently what happened in the U.S. case — the chances of the virus spreading during the journey are low.
“It’s very unlikely that they would be able to spread the disease to fellow passengers,” said Stephan Monroe, deputy director of CDC’s National Center for Emerging Zoonotic and Infectious Diseases.
“The Ebola virus spreads through direct contact with the blood, secretions or other body fluids of ill people, and indirect contact — for example with needles and other things that may be contaminated with these fluids.”
Travelers should take precautions by avoiding areas experiencing outbreaks and avoiding contact with Ebola patients.
“It is highly unlikely that someone suffering such symptoms would feel well enough to travel,” the International Air Transport Association said.