I don't think you'd find it in the nasal mucus any more than in other bodily fluids. The reason for the 4-5 day incubation period is that it takes time to build up numbers sufficient to cause the symptoms. At that time I would expect to find the virus in all bodily fluids, including the nasal mucosa. It being a hemorrhagic fever, there would be all kinds of leakage of blood through the tissues, including the nose and sinuses. I think the African nations are going to have to take some drastic measures to stop this epidemic. I don't think Ebola is one of those diseases that can be "carried" by a healthy person. It is highly virulent, which means that it takes very few of them to produce the illness. I don't think Ebola can "hide" in the nasal cavity, or if it does, not for very long. But that's just my best guess.