Ever since Thomas Duncan, the first Ebola patient diagnosed in the US, got on a plane in Monrovia and traveled to Dallas with the Ebola virus incubating in his body, there has been a lot of confusion about the risk of contracting the disease during travel. Now, with the news that the second Dallas health worker to contract Ebola flew from Cleveland the day before reporting to hospital with a fever, worry about the virus during air travel will surely peak.



So here's a refresher on how you can and can't get Ebola on a plane (or, for that matter, anywhere else):

Here are ways you could get Ebola on a plane:

1) You can get the Ebola virus if you have "direct contact" with the bodily fluids of a sick person, including blood, saliva, breast milk, stool, sweat, semen, tears, vomit, and urine. "Direct contact" means these fluids need to get into your broken skin (such as a wound) or touch your mucous membranes (mouth, nose, eyes, vagina).

2) So you could get Ebola on a plane by kissing or sharing food with someone showing symptoms of Ebola. You could get it if that symptomatic person happens to bleed or vomit on you during flight, and those viral fluids hit your mouth or eyes. You could also get it if you happen to be seated next to a sick individual, who is sweating profusely, and you touch that virulent sweat to your face. At least this last scenario is unlikely, however. One of the Ebola discoverers, Peter Piot, said, "I wouldn't be worried to sit next to someone with Ebola virus on the Tube as long as they don't vomit on you or something. This is an infection that requires very close contact."

The Ebola virus has been able to Live in semen for up to 82 days 3) You can get Ebola through sex with an Ebola patient. So you could get Ebola on a plane if you join the Mile High Club with an Ebola-infected individual. The virus has been able to live in semen up to 82 days after a patient became symptomatic, which means sexual transmission — even with someone who has survived the disease for months — is possible.

4) You can get Ebola through contact with an infected surface. Though Ebola is easily killed with disinfectants like bleach, if it isn't caught, it can live outside the body on, say, an arm rest or table. In bodily fluids, like blood, the virus can survive for several days. So if someone with infectious Ebola gets his or her diseased bodily fluids on a surface that you touch — an airplane seat, for example — and then you put your hands in your mouth and eyes, you could get Ebola on an airplane.



5) This is a very unlikely situation, but: you can get the virus by eating wild animals infected with Ebola or coming into contact with their bodily fluids — on a plane. The fruit bat is believed to be the animal reservoir for Ebola, and when it's prepared for a meal or eaten raw, people get sick. So you could get Ebola in flight by bringing some under-cooked bat meat onto the aircraft and having it for supper.





Here are ways you can't get Ebola on a plane:

1) You can't get Ebola from someone who is not already sick and showing symptoms. The virus only turns up in people's bodily fluids after a person starts to feel ill, and only then can they spread it to another person. So if you were sitting on a plane next to someone who had Ebola but wasn't yet showing symptoms or infectious, you would not get Ebola.



The second Dallas health worker to contract the virus flew the day before she reported to hospital with a fever and had a temperature of 99.5. If true, it's unlikely that she would have been infectious at the time, but health officials are taking precautions and following up with everybody on the flight.



Ebola isn't easy to transmit. 2) It's very rare to transmit Ebola through coughing or sneezing. The virus isn't airborne, thankfully, and experts expect that it will never become airborne because viruses don't change the way they are transmitted.



Still, the Centers for Disease Control and Prevention offered this cautionary note: "If a symptomatic patient with Ebola coughs or sneezes on someone, and saliva or mucus come into contact with that person's eyes, nose or mouth, these fluids may transmit the disease." This happens rarely and usually only affects health workers or those caring for the sick.



So the possibility of transmission on a plane by coughing or sneezing exists — but it is small. It would have to go something like this: An Ebola patient would have to cough on the hand of the person sitting next to them, releasing some amount of mucus or saliva. The person being coughed on would then have to (say) rub his or her eye with that hand, allowing the disease into the body.

The bottom line: Ebola is difficult, but not impossible, to catch even in confined spaces like planes



Ebola isn't easy to transmit. The scenarios under which Ebola spreads are very specific. As the World Health Organization — which does not recommend travel bans — put it, "On the small chance that someone on the plane is sick with Ebola, the likelihood of other passengers and crew having contact with their body fluids is even smaller." They also point out that people who are sick with Ebola "are so unwell that they cannot travel."



Ebola doesn't spread quickly, either. An Ebola victim usually only infects one or two other people. Compare that with HIV, which creates four secondary infections, or measles with 17.



So far, there have been three known Ebola cases originating in the US. There are upwards of 8,000 in West Africa. That's where experts say the worry and fear about Ebola contagion should be placed.