Hepatitis D
Hepatitis D is a viral infection of the liver caused by the hepatitis D virus (HDV), which is unique in that it can only infect individuals who are also infected with hepatitis B virus (HBV). This condition can occur as a simultaneous infection with hepatitis B (coinfection) or as a subsequent infection in someone with chronic hepatitis B (superinfection). There are two forms of hepatitis D: acute and chronic, with the latter potentially leading to severe liver damage, cirrhosis, or death. Symptoms of hepatitis D may include fatigue, loss of appetite, abdominal pain, and nausea, which can often be mistaken for other illnesses.
Transmission of HDV occurs through exposure to infected blood or body fluids, typically through shared needles or contact during childbirth. Diagnosis involves a series of blood tests to detect HDV antigens and liver enzyme levels. While there is no specific cure for hepatitis D, treatment focuses on managing symptoms, especially for acute cases. Preventive measures include vaccination against hepatitis B, as individuals without hepatitis B cannot contract hepatitis D. Globally, hepatitis D remains a significant health concern, affecting millions and contributing to liver disease.
Hepatitis D
Anatomy or system affected:Liver
Also known as: Delta agent, delta hepatitis, hepatitis D virus
Definition
Hepatitis D is a viral infection of the liver caused by the hepatitis D virus. The hepatitis D virus is infective only in persons who are also infected with active hepatitis B. Hepatitis D can initiate an infection at the same time as the initial hepatitis B infection (coinfection), or it can infect a person with lifelong (chronic) hepatitis B infection (superinfection). There are two types of hepatitis D: acute and chronic. Chronic infection can cause serious liver damage, or cirrhosis, and death.
Causes
Hepatitis D is caused by the hepatitis delta virus (HDV), which is a small, circular, enveloped ribonucleic acid (RNA) virus. HDV requires the help of a Hepadnavirus (hepatitis B virus, or HBV) for its own replication. The delta virus is an incomplete viral particle. Its companion virus, HBV, actually forms a covering over the HDV particle.
Risk Factors
Hepatitis B infection may occur simultaneously when HDV is spread, or the person may already have hepatitis B. In either case, the transmission of HDV can occur in one of several ways: when blood from an infected person enters the body of a person who is not infected; through contact with other body fluids, such as semen, vaginal fluids, or saliva; and through contact with shared needles or through needle-sticks or other sharp exposures on the job. Rarely, transmission can occur from an infected woman to her fetus during childbirth.
Symptoms
The symptoms of hepatitis D may include fatigue, loss of appetite, diarrhea, dark urine, abdominal pain, muscle pain, joint pain, sore throat, nausea, and vomiting. These early symptoms may be confused with symptoms common to the stomach flu.
Screening and Diagnosis
A doctor can test for hepatitis D through a series of blood tests that identify HDV antigens. Diagnostic tests may include liver enzyme tests, which look at certain levels of liver enzymes in the blood. Other tests will look for antibodies that the body has made against the hepatitis D virus.
Treatment and Therapy
Each type (acute and chronic) of hepatitis D is treated differently. There are no specific medicines that can cure hepatitis D, so treatment for acute hepatitis D is focused on dealing with symptoms or complications. Even without specialized treatment for acute hepatitis D, most people recover completely within a few weeks.
Although there are some indications that certain medicines used to treat hepatitis B may be effective against hepatitis D, there are no drugs that are approved to treat a chronic hepatitis D infection. These medicines include alpha interferon and pegylated alpha interferon. There is no consent, however, on how much of these medicines should be used or on a timeline for use.
Prevention and Outcomes
The best prevention against hepatitis D infection is to obtain a vaccination against hepatitis B. Persons who are not infected with hepatitis B cannot contract hepatitis D. In 2020, an article published in the Journal of Hepatology suggested that over 12 million people globally had experienced hepatitis D infection and that it remained a key contributor to liver disease worldwide.
Bibliography
Boyer, Thomas D., Teresa L. Wright, and Michael P. Manns, eds. Zakim and Boyer’s Hepatology: A Textbook of Liver Disease. 5th ed. Philadelphia: Saunders/Elsevier, 2006.
Feldman, Mark, Lawrence S. Friedman, and LawrenceJ. Brandt, eds. Sleisenger and Fordtran’s Gastrointestinal and Liver Disease: Pathophysiology, Diagnosis, Management. New ed. 2 vols. Philadelphia: Saunders/Elsevier, 2010.
Stockdale, Alexander J., et al. “The Global Prevalence of Hepatitis D Virus Infection: Systematic Review and Meta-Analysis.” Journal of Hepatology, vol. 73, no. 3, April 23, 2020, pp. 523-532. Journal of Hepatology, www.journal-of-hepatology.eu/article/S0168-8278(20)30220-8/fulltext. Accessed 28 Feb. 2023.
Taylor, J. M. “Hepatitis Delta Virus.” Virology 344 (January, 2006): 71-76.