Hepatitis D: definition, symptoms, diagnosis and treatment

By Cristiano Antonino On Apr 27, 2023

Hepatitis D is an inflammation of the liver caused by the infection of two viruses, the hepatitis B virus (HBV) and the hepatitis D virus (HDV)

The latter belongs to the class of viruses termed ‘defective’, as it requires the simultaneous presence of the B virus in order to replicate.

As a corollary of this condition, the development of hepatitis D can only occur in HBV-positive individuals, i.e. those infected with hepatitis B.

There are two modes of HDV infection:

the Delta co-infection, a condition in which transmission of the D and HBV viruses are simultaneous;
Delta super-infection, a condition in which a person who is already a chronic HBV carrier becomes infected with the Delta virus.
Hepatitis D can be short-lived (acute) or develop slowly and over time (chronic).

When D virus infection occurs in a person with chronic hepatitis B, in 70-90% of cases it accelerates progression to a more serious disease.

The majority of Delta infections present as acute hepatitis of varying severity depending on the presence or absence of pre-existing liver damage.

The infection tends to become chronic in 90% of cases.

The incubation time can be up to six months as in the case of Hepatitis B or C.

Epidemiology of hepatitis D

It is estimated that there are approximately 10 million people worldwide infected with HDV.

Similarly to the Hepatitis B virus, the Hepatitis D virus is present globally.

Although its prevalence is higher in developing areas and among people with a low socio-economic status.

According to a study published in the Journal of Hepatology in 2020, it appears that Hepatitis D (or Delta) affects about 5% of people who are infected with Hepatitis B.

The study shows high prevalences of hepatitis D in certain regions, such as Mongolia, Moldova and some Middle Eastern African countries.

Globally, the overall number of HDV infections has declined sharply since the 1980s.

As for the different genotypes, genotype I is the most widespread, genotype II is predominant in Japan and Taiwan, and genotype III is only present in the Amazon.

It should also be noted that some investigations have revealed that in Europe and the US, approximately 25-50% of the cases of fulminant hepatitis initially considered to be cases of Hepatitis B were in reality caused by the D virus.

Viral hepatitis D virus is transmitted by blood or body fluids of an infected person

More specifically, contagion occurs

sexually
through blood by transfusion and transplantation of infected organs
through biological liquids (bile, nasal discharge)

and again

by vertical transmission, from mother to child
through the use of contaminated needles and surgical instruments or toiletries.

People infected with hepatitis D should

take appropriate precautions to avoid spreading the disease to sexual partners
do not donate blood, sperm or organs
notify your doctor and dentist
consult your doctor if you wish to become pregnant (as seen, vertical transmission from mother to child, although rare, is possible).

Symptoms and complications of hepatitis D

Acute infection with hepatitis D and B viruses often generates no overt symptoms.

A person may therefore be unaware that he or she has contracted it and contribute to the spread of the infection.

If complaints do occur, usually within three months of transmission, they may include

fever
muscle and joint pain
malaise
tiredness
loss of appetite
abdominal pain
dark urine
pale, grey-coloured stools
epidermal itching
jaundice, i.e. yellowing of the eyes and skin.

Chronic hepatitis may also not cause any noticeable symptoms for long periods, until liver failure (a condition in which the liver ceases to function properly) occurs.

This situation can be detected through certain blood tests.

For example, the search for transaminases, enzymes normally contained within liver cells that are released in large quantities when liver cells die (necrosis) due to inflammation.

In these cases, other symptoms may also appear such as:

jaundice
swelling of the legs, ankles and feet
confusional state
blood in the stool or vomiting

In more serious cases, a liver tumour (hepatocarcinoma) could develop with the following symptoms

unjustified weight loss
feeling very full after a meal (even with small amounts of food)
malaise
jaundice, i.e. yellowing of the skin and eye.

A hepatitis D infection can lead to serious complications that include:

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cirrhosis of the liver, chronic inflammation caused by hepatitis D infection can impair the liver’s ability to function.
liver failure, acute liver failure is a condition in which the vital functions of the liver are impaired.
liver cancer, people with chronic hepatitis D infection have an increased risk of developing liver cancer (hepatocarcinoma). In the presence of the latter, surgery or a liver transplant may be necessary
kidney disease or inflammation of the blood vessels.

Diagnosis, treatment and prevention

Hepatitis D is diagnosed by taking a blood sample and testing for HDV antibodies and HDV-RNA.

About three months after infection, antibodies directed against the D virus appear: their persistence for months or years indicates that the subject is infected and that there is chronicity of the disease.

The disappearance of the antibodies is an indication of recovery.

To date there is no specific cure for acute or chronic hepatitis virus infection.

It is generally treated with drugs, such as pegylated interferon (PEG-IFNα2a), which aim to eliminate the virus or keep it under control to reduce the risk of liver damage.

Potential new drugs, such as prenylation inhibitors (directed against the hepatitis D virus) or virus entry inhibitors, are under investigation.

Against this background, one can deduce the fundamental function of prevention in combating hepatitis D.

The main focus in this respect is undoubtedly the vaccine. Although there is no specific one against hepatitis D virus infection, the hepatitis B vaccine is also able to protect against hepatitis (due to the aforementioned defective nature of the Delta virus).

The vaccine is safe and effective; it does not contain the virus, but only some of its portions artificially produced in the laboratory.