Definition of Delta agent (Hepatitis D):

Delta agent is a type of virus called hepatitis D that causes symptoms only in people who have a hepatitis B infection.

Causes, incidence, and risk factors:

Hepatitis D virus (HDV) is only found in people who carry the hepatitis B virus. HDV may make a hepatitis B infection or existing hepatitis B liver disease worse. It can cause symptoms in people with hepatitis B virus who never had symptoms.

Hepatitis D infects about 15 million people worldwide. It occurs in 5% of people with hepatitis B.

Risk factors include:

• Having a hepatitis B infection in the past
• Carrying the hepatitis B virus
• Receiving many blood transfusions
• Intravenous (IV) drug abuse
• Men having intercourse with other men
• Being infected while pregnant (can pass the virus to the baby)