There is still sufficient problems. Take the Bird Flu back when we were in panic mode. Just because you concocted a disease that's lethal doesn't mean that it's easily transmittable. So in the process of trying to make an Air Born Ebola you end up infecting yourself long before you make it an easily transmissible version. Sure you could be a slow moving disease bomb, but if the infection rate is like how the Bird Flu was when you practically had to get bird feces on your hands then put it in your mouth cross infection becomes unlikely. Even regular Ebola wouldn't spread very well here. In Africa it spreads so easily mostly due to some archaic barrial rights where all the women prepare the body. Here we're so paranoid about corpses that only a special medial technical gets to extract the fluid embalm, and all in a very sanitary way.