Via National Geographic: ‘There are few direct flights from West Africa to the U.S., so most feverish passengers entering American airports will have something far more routine and less risky than Ebola.

Ebola is contagious only when symptomatic, so someone unknowingly harboring the virus would not pass it on, Monroe said.

Even passengers showing symptoms are unlikely to pass the disease on to fellow travelers, he said.Blood and stool carry the most virus—which is why those at highest risk for Ebola infection are family members who care for sick loved ones and health care workers who treat patients or accidentally stick themselves with infected needles.Theoretically, there could be enough virus in sweat or saliva to pass on the virus through, say, an airplane armrest or a nearby sneeze, said Stephen Morse, an epidemiologist and virologist at the Mailman School of Public Health at Columbia University in New York. But droplets would still need a way to get through the skin.’