The answer is given in Surah Baqarah
This is the Book; in it is guidance sure, without doubt, to those who fear Allah. [2-2]
The Quran has been sent as a guidance and mercy for all of mankind, whoever believes in it will follow it.
From that we can say that the guidance in it is accepted by the Muslims (or
those who fear Allah) and is rejected by the non-Muslims.
Regarding the disease part, I think you answered it yourself. Once the disease is cured inshallah, there will be relief.