hepatitis b is an infectious hepatitis caused by the hepatitis b virus hbv this infection has two possible phases 1 acute and 2 chronic acute hepatitis b refers to newly acquired infections affected individuals notice symptoms approximately 1 to 4 months after exposure to the virusepatitis b is an infectious hepatitis caused by the hepatitis b virus hbv this infection has two possible phases 1 acute and 2 chronic acute hepatitis b refers to newly acquired infections affected individuals notice symptoms approximately 1 to 4 months after exposure to the virus