What is hepatitis D (HDV)?
The liver is a vital organ of the human body as it is responsible for important functions such as digestion, detoxification, storage of vitamins, metabolism and immunity. It plays a role in almost all bodily functions and can be the target of various pathogens, e.g. HDV.
Hepatitis D (HDV) only occurs in conjunction with hepatitis B
Hepatitis D virus (HDV) or delta virus is an incomplete ribonucleic acid virus meaning it needs the presence of another virus (in this case the hepatitis B virus, HBV) in order to develop and grow. This is the only way for the virus to infect new hepatocytes. HDV appears to replicate exclusively in the liver. Due to its dependence on HBV, HDV can only be transmitted in the presence of a HBV infection.
Either the infection with HBV and HDV occurs at the same time (simultaneous infection) or the person is already chronically ill with hepatitis B (HBV) at the time of the HDV infection (superinfection).
The exact relationship between the two viruses is not yet known.
Superinfection or Simultaneous Infection?
Simultaneous infection:
Acute hepatitis as a frequent secondary disease
Simultaneous HBV/HDV infection can cause acute hepatitis. Since HDV is an incomplete virus, infection with HDV can only occur if HBV has already infected the liver cells.
The complex interplay between the two viruses means that the clinical picture of the simultaneous HBV/HDV infection can lead to moderate to severe hepatitis, which in rare cases can progress rapidly.
The transmission time of hepatitis D (HDV) depends on the intensity of HBV co-infection in the body, which also determines the transmission time of hepatitis B (HBV). Development into chronic hepatitis D (HDV) occurs very rarely.
Superinfection:
Chronic course almost inevitable
The clinical picture of superinfection varies, but it causes acute hepatitis with a relatively short period of infection.
In this case, infection with HDV can exacerbate chronic hepatitis B, so that a "new" hepatitis appears as rapidly progressing liver inflammation.
Without treatment, chronic hepatitis D (HDV) develops in up to 90% of cases of superinfection. In rare cases, superinfection with HDV causes moderate hepatitis.
According to current research, around 12 million people worldwide are infected with HDV with 5% of those infected with HBV. HDV infection can lead to acute or chronic hepatitis D (HDV).
Chronic infection with HBV/HDV is characterised by a more rapid course, an increased probability of liver cirrhosis and triple the risk of developing liver cancer (hepatocellular carcinoma).
Worldwide prevalence
According to the WHO, there are regions in which the occurrence of the HDV virus is observed particularly frequently: Africa (Central and West Africa), Asia (Central and North Asia as well as Vietnam, Mongolia, Pakistan, Japan, Taiwan, China), Pacific Islands (Kiribati, Nauru), Middle East (all countries), Eastern Europe (Eastern Mediterranean, Turkey), South America (Amazon Basin) and Greenland. However, global estimates and geographic information are incomplete because many countries do not test for HDV.
Sources
Physiology, Liver. Kalra A, Tuma F. [Updated 2018 Dec 18]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2020 Jan-.
Clinical features of hepatitis D. Farci P1, Niro GA. Semin Liver Dis. 2012 Aug;32(3):228-36.
Pathogenesis of and New Therapies for Hepatitis D Koh, Christopher et al. Gastroenterology, Volume 156, Issue 2, 461 – 476.e1
Stockdale AJ, Kreuels B, Henrion MYR, Giorgi E, Kyomuhangi I, de Martel C, Hutin Y, Geretti AM. The global prevalence of hepatitis D virus infection: Systematic review and meta-analysis. J Hepatol. 2020 Sep;73(3):523-532
https://www.who.int/fr/news-room/fact-sheets/detail/hepatitis-d Stand 09/03/2020
Important stages from diagnosis to therapy
It is difficult to distinguish the symptoms of acute viral hepatitis D from another form of acute hepatitis.
If you have not been vaccinated against hepatitis B (HBV) and are at risk of contracting HBV or HDV , see your doctor for clarification and guidance. If you knowingly become acutely infected with hepatitis B (HBV), there is the possibility of post-exposure prophylaxis, which must be initiated within forty-eight hours
To find out whether you have contracted HBV or HDV, your blood will be tested in a laboratory.
If a HBV infection is confirmed, testing for hepatitis delta (HDV) should then take place immediately. Additionally, you should receive a referral to a liver specialist (hepato-gastroenterologist).
A hepatologist is a medicalspecialists for liver disease who will examine you in the hospital or in a doctor's office.
A HDV test should generally be performed in patients infected with HBV. More liver-specific tests can be done in the hospital.
Based on the results of the additional tests, your hepatologist, supported by a multidisciplinary medical team, will recommend and prescribe an appropriate HBV/HDV treatment.
Depending on the type of treatment prescribed, you will receive this directly at the hospital or you can obtain the medication from a pharmacy.
It is important to take your medication as directed and to read the patient information leaflets carefully.
Your hepatologist will monitor your treatment to check its effectiveness, as well as monitor the progression of the disease to detect any complications or signs of worsening.
Be assured that you are not alone on this journey or in dealing with this disease. It is very important to have someone to talk to. This can be a friend or family member. A patient organisation can also be a helpful contact point.