Hepatitis D is transmitted in a very similar way to hepatitis B. It is mainly transmitted by blood, mother-to-child transmission, and sexual contact, and is a defective virus that must be encapsulated by hepatitis B surface antigen in the blood. The hepatitis D virus must also be assisted by the hepatitis B virus when it replicates as well as causes liver damage. When infected with the hepatitis D virus, it is important to treat the cause of the hepatitis B virus that it is dependent on, which means aggressive treatment of hepatitis B. This will eliminate the hepatitis D virus. If left untreated, the disease will progress, such as to cirrhosis or even liver cancer. Hepatitis B can be controlled by applying interferon or oral nucleotide analogues to inhibit the replication of the hepatitis B virus.