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Understanding hepatitis D

What are the different stages of infection of the hepatitis D virus?

An infection with the hepatitis D virus (HDV) can proceed in different ways: Either as a simultaneous infection or as a superinfection.

Simultaneous infection: Acute hepatitis as a frequent secondary disease

Simultaneous HBV/HDV infection can cause acute hepatitis. Since HDV is an incomplete virus (i.e. it requires the presence of another virus), spread of HDV can only occur if HBV has also infected the liver cells. The severity of the infection of HDV is limited by that of HBV.

A mild disease course of the HBV infection can lead to a termination of the infection with the HDV, while a pronounced clinical picture of the HBV infection supports the multiplication and thus the dangerousness of the HDV.

This complex interplay between the two viruses means that the clinical picture of simultaneous HBV/HDV infection can lead to moderate to severe or acute, and in rare cases fulminant, liver inflammation. The incubation period of hepatitis D depends on the intensity of the HBV co-infection in the body, which in turn determines the incubation period of hepatitis B. The course of acute hepatitis D depends on the intensity of the HBV co-infection in the body. The course of acute hepatitis can occur in one or two phases. Simultaneous HBV/HDV infection usually causes moderate hepatitis, which is clinically indistinguishable from monoinfection with HBV and generally recovers completely. Development of chronic hepatitis D occurs in less than 2% of cases. In rare cases, simultaneous HBV/HDV infection can also cause fulminant liver inflammation.

Superinfection: Chronic course almost inevitable

In the case of a superinfection, the clinical picture of HDV infection is different. The clinical picture of a superinfection is variable, but it generally represents acute hepatitis with a relatively short incubation period.

In this case, infection with HDV can exacerbate chronic hepatitis B by causing liver failure or a "novel" hepatitis in the asymptomatic patient and carrier of HBV. Superinfection with HDV can also cause fulminant liver inflammation. Without treatment, the development of chronic hepatitis D is observed in up to 90 % of superinfection cases. In rare cases, superinfection with HDV causes moderate hepatitis and HBV is cleared from the body.1

Consequences of untreated hepatitis D infection

  • Hepatitis means inflammation of the liver cells. If hepatitis D is not recognised and treated, the liver is permanently exposed to this inflammation. 
  • The body reacts to this by initially building up functionless connective tissue in the liver. This increased formation of connective tissue is called fibrosis. 
  • If the inflammatory process progresses, more and more liver cells die, leaving behind scarred tissue. This scarring is called cirrhosis. 
  • In advanced liver cirrhosis, the liver can no longer perform its tasks adequately, and further health complications occur, including liver failure. In addition, cirrhosis increases the risk of liver cancer.2

References

  1. Farci P., Niro G.A. Clinical features of hepatitis D. Semin Liver Dis. 2012 Aug;32(3):228-36.
  2. AWMF-Register-Nr.: 021/011 Prophylaxis, Diagnosis and Therapy of Hepatitis B Virus Infection–The German Guideline;880