Maybe his family all already had it and are immune ...
Or maybe since they knew he had it, they took precautions. Or perhaps they've all caught it and it's not being reported. Have they been heard from lately?
It would be hard to keep victims of ebola secret unless they themselves don't present themselves for treatment.
The pregnant lady in Liberia he had extensive contact with was said to have malaria. Only near the end or after her death did they say it was ebola. The way I read the article in the LAT which was the most extensive I've seen, nobody WANTED to believe she had ebola.