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What is Hepatitis D?

Hepatitis D virus (HDV) is an RNA virus that is structurally unrelated to hepatitis A, hepatitis B, or hepatitis C virus. It was discovered in 1977. HDV causes a unique infection that requires the assistance of viral particles from hepatitis B virus (HBV) to replicate and infect other hepatocytes. Its clinical course is varied and ranges from acute, self-limited infection to acute, fulminant liver failure. Chronic liver infection can lead to end-stage liver disease and associated complications.

Simultaneous disease with HBV and HDV is known as coinfection and results in fulminant liver failure in 1% of individuals. Complete clinical recovery and clearance of HBV and HDV coinfection is the most common outcome. Chronic infection with HBV and HDV occurs in less than 5% of patients.

Infection with HDV in a patient who is already positive for the hepatitis B area antigen (HBsAg) is known as superinfection and results in fulminant liver failure in 5% of patients. Approximately 80-90% develop chronic HDV infection. These patients progress more rapidly to develop cirrhosis and may develop hepatocellular carcinoma.

What are the causes of Hepatitis D?

There is only one cause of hepatitis D - an infection with the hepatitis D virus (also known as HDV or the delta hepatitis agent). The hepatitis D virus is a small RNA virus that belongs to the genus Deltavirus. However, there is one important difference between hepatitis D and other types of viral hepatitis. A person who is infected with the hepatitis D virus must also have a hepatitis B infection in order for the hepatitis D virus to multiply. This is not the case with other types of viral hepatitis.

When a person is infected with the hepatitis D virus (and either has active hepatitis B or is co-infected with hepatitis B at the same time), the virus is able to enter liver cells from the blood and then use those cells to make more copies of the hepatitis D virus. As more and more of the hepatitis D virus is made in the liver cells, they can become damaged and may even die.

A person infected with the hepatitis D virus may acquire a sudden onset of fever, extreme tiredness, nausea, a lack of appetite, abdominal pain (or stomach pain), and yellowing of the skin or whites of the eyes (known as jaundice). Yet, not everyone infected with the hepatitis D virus will develop symptoms. With hepatitis D, a person can also develop a long-term liver infection (known as chronic hepatitis D).

Specific Hepatitis D Symptoms

For a person with hepatitis D, symptoms (especially early symptoms) may include one or several of the following:

Fatigue Excessive tiredness Not feeling very hungry Nausea or vomiting Diarrhea A low-grade fever Muscle pain Joint pain Sore throat Mild abdominal pain (or stomach pain) Dark urine Light-colored stool.

Oftentimes, these early symptoms may be confused with those commonly seen with the stomach flu (see Stomach Flu Symptoms).

Jaundice (yellowing of the skin or the whites of the eyes) usually occurs several days after early symptoms of hepatitis D first appear. However, it may occur up to two weeks after symptoms begin. At this point, early symptoms tend to improve; but other new symptoms, such as abdominal pain (or stomach pain) on the right side, may appear.

One serious complication that can occur during this acute hepatitis D infection is fulminant hepatitis - a serious condition that results in liver failure. Up to 5 percent of people who get infected with the hepatitis B virus at the same time as the hepatitis D virus will develop fulminant hepatitis. Up to 20 percent of people with chronic hepatitis B will develop fulminant hepatitis with an acute hepatitis D infection. Some factors that can increase the risk of developing fulminant hepatitis include:

Being older Having severe liver disease (cirrhosis) Having had a liver transplant. Prognosis

The prognosis is excellent for patients with coinfection in whom treatment eradicates both viruses. The prognosis is variable for patients who are superinfected. It depends on the duration and severity of HBV infection, alcohol consumption, comorbid illnesses, and age.

In patients who undergo liver transplantation for chronic liver disease secondary to HBV and hepatitis D virus (HDV) infection, HDV seems to suppress the replication of HBV in the transplanted liver and may help to prolong graft survival. However, fulminant hepatitis from recurrent HBV and HDV infection in the transplanted liver has resulted in patient death or the need to retransplant.