Hepatitis D

Synonyms in the broadest sense

Liver inflammation, liver parenchymal inflammation, viral hepatitis, autoimmune hepatitis, toxic hepatitis

definition

Hepatitis D is an inflammation of the liver caused by the hepatitis D virus (also: hepatitis delta virus, HDV, formerly delta agent). However, this is only possible if an infection with the hepatitis B virus took place either at the same time or before. 5% of patients who are permanently infected with hepatitis B are co-infected with the hepatitis D virus.

The hepatitis D virus

The hepatitis D virus (HDV) is a very rare type of virus. It is an incomplete ("naked") virus, which you also have Virusoid is called. The peculiarity is the lack of the virus envelope, which, however, is required to dock onto foreign cells and to introduce the virus genetic material into the host cell. Therefore, the HDV uses the hepatitis B virus (HBV) as a helper. Thus, the hepatitis D virus is only able to multiply in the presence of the hepatitis B virus. It binds to proteins in the envelope of the HBV that HBsAg and uses the same path of infection as the hepatitis B virus.

If the HDV has injected its genetic material (RNA = ribonucleic acid) into the host cell, this cell builds the foreign one RNA into its own metabolism and now produces the proteins of the virus. Once the individual virus components have been formed, they assemble and the new virus leaves the cell, which is thereby destroyed. This is how HDV, which does not have its own metabolism, multiplies.

There are 3 different genotypes of HDV, i.e. 3 different RNA types.

• Genotype I is found in the western world, Taiwan, and Lebanon.
• Genotype II is common in East Asia and
• Genotype III in South America.

In certain areas of the world, such as the Mediterranean region, Romania, the Middle East, Africa or the Amazon region, so-called hepatitis D endemics occur at times. Endemic is the constant occurrence of a disease in a certain region. Sporadic hepatitis D can be found on all continents, especially within the hepatitis B risk groups, i.e. drug addicts (intravenous drugs), sex tourists, heterosexuals and homosexuals with frequently changing Sex partners, recipients of blood reserves, dialysis patients, medical staff, etc.

Transmission and Symptoms

The hepatitis D virus is mainly transmitted parenterally (via blood and body fluids), sexually or perinatally (when a child is born by an infected mother).
The incubation period (time from the time of infection to the onset of the disease) is 3-7 weeks for HDV.

The symptoms correspond to those of hepatitis A:

In the so-called prodromal stage, which lasts 2-7 days, flu-like symptoms such as increased temperature and fatigue appear, as well as nausea, loss of appetite, tenderness in the right upper abdomen and possibly diarrhea. Other symptoms are an acute rash and joint pain, but these do not always occur.
In the second stage (4-8 weeks) the virus settles in the liver. Adults now have jaundice (Jaundice). In addition to the discoloration of the white dermis in the eye, as well as the entire surface of the body, this liver manifestation manifests itself in a dark color of the urine with simultaneous discoloration of the stool. The liver is now significantly enlarged and painful. In approx. 10-20% of the cases an enlargement of the spleen and lymph node swelling can be found at this stage.

Diagnosis

On the one hand, the hepatitis D virus can be transmitted at the same time as the hepatitis B virus (simultaneous infection). On the other hand, a patient with existing hepatitis B can become infected with the HD virus (superinfection). Depending on which infection is present, different laboratory evidence is possible.
In any case, a laboratory blood test should be carried out. The detection of hepatitis D-specific antigen is often better possible with a superinfection than with a simultaneous infection.
In addition, the antigen is usually only detectable within the first to second week of the acute infection.
If the hepatitis D antigen is already negative, the anti-HDV IgM antibody can be detected in the late acute stage of infection. If there is a permanent (chronic) infection, it can also persist (be permanently detectable).
The IgM antibody is the antibody that acts less specifically against the virus and is the first to be formed when an infection occurs.

The anti-HDV IgG can be detected as an additional antibody in the later course. IgG antibodies are more specific against the virus. In the case of simultaneous infection, it can be detected in the blood approx. 4-6 months after the onset of the disease. In the case of a superinfection, the anti-HDV IgG antibodies can be tested positive in the blood just 4 weeks after the onset of the disease. If the test for antigen or antibody is uncertain, but there is still a suspicion of hepatitis D infection, the detection of HDV-RNA by means of PCR (polymerase chain reaction) can be used. The RNA is the genetic material of the hepatitis D virus.
In addition, the blood should be tested for antigens and antibodies of the hepatitis B virus.

incubation period

The incubation period is the period between infection with the virus and the first appearance of clinical symptoms. The incubation period for hepatitis D can vary between 4-12 weeks, i.e. up to 4 months. If it is a superinfection - a hepatitis D infection with existing hepatitis B - the time to onset of the disease is usually shorter than with a simultaneous infection.

Course and Therapy

For the course of hepatitis D, it is important whether the patient was infected with the hepatitis B virus and the hepatitis D virus at the same time (simultaneous infection) or first with HBV and later with HDV (superinfection).
Superinfection is far more common and has a much worse prognosis. The so-called "second hit“A second severe liver disease in a row often damages the liver so severely that it leads to chronic hepatitis. Here the acute liver inflammation does not heal even after 6 months and often leads to liver cirrhosis (connective tissue remodeling of the functional liver tissue) or a hepatocellular carcinoma (HCC, i.e. liver cancer) with it.

90% of all superinfections lead to chonic manifestation. Chronic HBV / HDV hepatitis is 3 times more likely to cause death than chronic HBV hepatitis alone.

A simultaneous infection with HBV and HDV leads to severe acute hepatitis, but 95% of all acute hepatitis caused by HDV heal completely.

There is currently no effective therapy against HDV. Therapies with alpha interferon are only successful in the rarest of cases and lead to a reduction in the virus count, which, however, usually increases again after the end of therapy. If the hepatitis B infection is also worthy of therapy, this can be done with so-called nucleoside analogues, which, however, are ineffective against HDV.
Liver-sparing medication can be given to treat typical hepatitis symptoms such as nausea, upper abdominal pain, vomiting and diarrhea. In addition, the patient should keep a strict bed rest and avoid alcohol and other substances that are harmful to the liver.
The last option in the case of severe liver damage is the transplant of a healthy organ.

vaccination

A direct vaccination against hepatitis D is not possible. However, there is a hepatitis B vaccination, which also protects against the hepatitis D virus, as it can only multiply in the presence of the hepatitis B virus. It is recommended to vaccinate against hepatitis B. The vaccination is generally carried out in the 2nd, 4th and 12th month of life.
If the vaccination was not given in infancy, 3 vaccinations must also be given in later life.
As a rule, a booster vaccination is then no longer necessary. The booster is only recommended if there is a high risk of infection. This is the case if, for example, the partner is infected with hepatitis B, if you come into frequent contact with people infected with hepatitis B (for example in a hospital) or if there is an immunodeficiency. In these cases, it should be refreshed every 10 years.