Hepatitis delta: what is it?

L’hepatitis delta, or hepatitis D, is a inflammation from liver which affects 15 to 20 million people worldwide; it is not very prevalent in France and is the cause of the most severe form ofchronic hepatitis. Like other forms of hepatitis, hepatitis delta is a liver disease characterized by inflammation. Initially acute, it can progress to chronic hepatitis if the infection exceeds six months.

The infection is caused by the hepatitis delta virus (HDV), the smallest virus known capable of infecting animal cells. When HDV replicates in hepatocytes (liver cells), the immune system attacks cells infected with the virus, causing inflammation of the liver.

Hepatitis B and delta: co-infection or superinfection

The hepatitis delta virus is said to be satellite. To be able to replicate, it needs the presence of another virus: that of hepatitis B (HBV). Thus, a person cannot be infected with hepatitis delta without having been previously infected with hepatitis B. The transmission of HDV is similar to that of HBV: it can occur perinatally (duringchildbirth), sanguine or sexual.

Infection by HBV and HDV can be simultaneous — this is called co-infection — or delayed when HDV infection occurs later — this is called superinfection. About 5% of people infected with hepatitis B are also infected with hepatitis D.

The prognosis differs greatly depending on the cases of co-infection or superinfection. In case of co-infection, the infection becomes chronic in less than 5% of cases, and the two viruses usually end up being eliminated. In case of HDV superinfection, the disease becomes chronic in 80% of cases.

In its acute phase, hepatitis delta, like most hepatitis, is minimally symptomatic. When she is, her symptoms are associated with a flu-like state: fatigue, vomiting, headaches, pains muscles and joints, sometimes jaundice. When it becomes chronic, like hepatitis B, hepatitis delta can develop into cirrhosisor in carcinoma hepatocellular — i.e. in liver cancer.

Hepatitis delta accelerates progression to cirrhosis

Its dangerousness comes from the fact that hepatitis delta accelerates the progression of the disease. The evolution towards cirrhosis of the liver occurs almost 10 years more rapidly in the case of delta hepatitis than in the case of hepatitis B mono-infection, by mechanisms that are still poorly determined.

Factors that cause chronic hepatitis delta to progress faster include excessive drinking alcoholHIV infection, or a metabolic syndrome.

Current treatments for chronic hepatitis delta are still not very effective and have significant and poorly tolerated side effects. If a vaccine against HDV does not exist, that against the hepatitis B virus remains the most effective means of preventing hepatitis D.