Hepatitis D is caused by a defective RNA virus (delta agent) that can replicate only in the presence of hepatitis B virus. Hepatitis B infection rarely occurs as coinfection during acute hepatitis B or as superinfection during chronic hepatitis, also type B.

Regurgitation
Regurgitation is the involuntary rising of gastric contents into pharynx, inside or outside the mouth, usually effortless and nonprojective.