I need some contribution ,in Liberia when the Ebola epidemic spread the whole country, one Lee Ann got sick and she was end up in a hospital,she was

I need some contribution ,in Liberia when the Ebola epidemic spread the whole country, one Lee Ann got sick and she was end up in a hospital,she was recovered after 4 weeks,while so many died and she stayed healthy and even though she too was exposed to the VIRUS. how come she survive