There is no evidence that it is air-transmissible. That is straight up fear-mongering. It is spread through bodily fluids. As the sickness progresses you are losing bodily fluids in a number of different ways in conditions that are not always sanitary.

Health workers get infected because they are physically dealing with patients in areas with some of the lowest healthcare standards in the world. Throw in some local wariness of foreign workers, and resistance to treatment until it's too late and it is totally understandable why 170 health-care workers have been infected.