Disease is a Manga/Manhwa/Manhua in (English/Raw) language, Mystery series, english chapters have been translated and you can read them here. You are reading chapters on www.mgeko.cc fastest updating comic site. The Summary is

Terminally ill lad, after losing his family in an incident, found out that hidden behind the disease was an extraordinary power. While pursuing the truth behind his family death, he himself, got dragged further down the mysterious dark abyss...