I wonder sometimes whether or not certain people at TOL are being intentionally dense, but I don't wonder that about you.
When someone coughs or sneezes, they might cough or sneeze out spit or mucus. Or did you think it was random magic that sometimes when you sneeze, a glob of mucus miraculously appears?
Ebola isn't an airborne virus, but the spit or mucus from a cough or sneeze could carry it. Coming in direct contact with that spit or mucus could contaminate someone, if the person doing the sneezing or coughing has already exhibited the symptoms of ebola.
Well, I'd hope they had the intelligence (or real-world experience) to understand that when someone coughs or sneezes, there might be some spit.