How did he get the disease? Sharing fluids with a sick person? Something about this doesn't make sense. If you can't get this from someone who isn't showing symptoms, there must be a lot of people sharing body fluids with Ebola patients in Africa.
Infected person is relatively safe while no symptoms have been developed. However, infection through blood transfusion or sexual intercourse is still possible.
All you need to do if swap bodily fluids, it does not need to be as much as you would get from sex or a blood transfusion. It can be as little as a little bit of blood, vomit or feces