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Hepatitis A is one of the most common viral hepatitis. It is usually self-limiting. It can be vaccinated to protect against infection.

Definition of hepatitis A:

Hepatitis A is an acute inflammation of the liver. It is caused by the picorna virus "hepatitis A virus" (HAV). It is usually self-limiting.

Epidemiology

Hepatitis A is widespread worldwide, especially in developing countries, where almost all children and adolescents are infected before adulthood. The annual incidence is around 1.5 million cases worldwide, with around 7,134 people dying from a hepatitis A virus infection in 2016.

It is important to keep an eye on the spread of hepatitis A and take appropriate measures, especially when traveling abroad. Continuous monitoring and the adaptation of preventive measures play a crucial role in further containing the spread of this infection.

Causes

Liver inflammation is caused by the hepatitis A virus. This virus, which belongs to the picornavirus family (Fam. Picornaviridae), is a unique single-stranded ss(+)-stranded RNA virus. With only a single serotype, it is known for its environmental stability, thermostability and remarkable resistance to disinfectants.

Humans act as the main host and remain the only relevant reservoir for HAV. These unique characteristics make the virus a challenge for containment. Understanding its structure and survival capabilities is crucial for the development of effective prevention and control measures. Research is focusing on how this environmental stability affects the risk of infection and how to effectively tackle this persistent virus.

Pathogenesis

Transmission of hepatitis A virus (HAV) is primarily fecal-oral through contact or smear infections. This can occur through the consumption of contaminated food, contact with infected water or through the sharing of utensils. Less common, but still possible, is transmission through anal-oral sexual contact. Contaminated blood products and syringes can also lead to infection with HAV.

After the virus has passed through the mouth, it enters the gastrointestinal tract and travels via the lymphatic system to the liver. There it multiplies in the cytoplasm of the liver cells, the hepatocytes. The virus can be detected in the blood around ten to twelve days after infection. Excretion takes place actively via the bile and the intestines, whereby there is a risk of infection during this phase. Interestingly, the highest titres of the virus can be measured around two weeks before the first symptoms appear.

In the liver, the virus leads to viremia in which CD8+ cytotoxic lymphocytes trigger cell death. The virus itself is not cytolytic. The increase in transaminases in the blood is an indicator, and the classic symptoms of hepatitis can be observed in a fulminant course. The average time between infection and the onset of the disease is around 28 days, although the incubation period can vary between 14 and 50 days.

Symptoms

Especially in children, hepatitis A infection often occurs without any recognizable symptoms. The signs differ only slightly or not at all from other forms of hepatitis. The disease breaks out suddenly and often manifests itself with fever, a general feeling of illness, skin rash, reduced appetite, nausea, abdominal pain, vomiting and diarrhea. About 80% of affected adults also develop jaundice, also known as icterus, but this symptom complex is rare in children.

During the physical examination, an enlarged liver (hepatomegaly) can be detected in many patients. About 25% of cases also show enlargement of the spleen (splenomegaly). In addition, signs of cholestasis may occur, including jaundice, brown discoloration of the urine, discoloration of the stool, itching and occasionally transient scarlatiniform skin rashes.

It is important to emphasize that only in very rare cases (0.01-0.1%) does hepatitis A take a fulminant or even fatal course. Early recognition of symptoms, especially in at-risk groups, enables adequate medical care and helps to prevent serious complications.

Diagnosis

Hepatitis A is often not clearly symptomatic compared to other viral hepatitis. Physical examination may reveal signs such as an enlarged liver and yellowing of the eyes, particularly the sclera and skin, although jaundice is not necessarily present. However, a reliable diagnosis is made through laboratory tests.

A significant increase in transaminases in the blood is the first sign of hepatitis. The de-ritis quotient from the transaminases GOT and GGT is normally below 1, but can be elevated in rare fulminant courses. Liver synthesis parameters such as total protein in the blood are affected, in particular the albumin level is reduced. Coagulation is slowed down as the cell death means that not enough coagulation-promoting substances can be produced in the inflamed liver. In a very fulminant course with acute liver failure, cholinesterase may also decrease.

The hepatitis A virus is detected in serum or stool. Antibodies against HAV can be detected in both using antigen ELISA or HAV RNA using RT-PCR. Anti-HAV IgM antibodies in serum are an indicator of a recent HAV infection and can be detected at the first symptoms. They help to distinguish a current infection from a previous infection or immunity acquired through vaccination. In individual cases, anti-HAV IgM can also be elevated for a short time after vaccination.

An elevated anti-HAV-IgG antibody indicates a past but no longer current HAV infection or successful immunization through vaccination. A precise diagnosis is crucial for adequate treatment and management of hepatitis A.

Therapy

Most hepatitis A infections heal spontaneously on their own and do not require specific causal therapy. Support is limited to symptomatic measures and the full recovery process can take weeks or months. Bed rest may be recommended during the infection, depending on the patient's condition, but in most cases strict bed rest is not necessary.

To avoid putting additional strain on the liver, medications that are broken down by the liver and are toxic to the liver, such as paracetamol and various antiemetics (anti-nausea and anti-vomiting medications), should be avoided during recovery. In the case of long-term medication, it is advisable to consult your doctor to clarify which medication can be discontinued and which must continue to be taken. Alcohol consumption should be avoided completely. During the symptoms, the diet should be changed to a high-carbohydrate and low-fat diet.

Hospitalization is usually only necessary in the case of a fulminant course of hepatitis A, especially if acute liver failure occurs. The treatment regimen then depends on the specific requirements of this serious complication. Early medical care and adherence to recommendations can support the recovery process and minimize the risk of complications.

Prognosis

Most hepatitis A infections have no lasting consequences. An icteric course with jaundice is observed in less than 10% of cases in children under six years of age, in around 45% of cases in children between six and 14 years of age, and in more than 75% of cases in adults. A fulminant course is comparatively rare at 0.2%. In carriers of hepatitis B viruses, however, the risk of a fulminant course increases to up to 10%.

The mortality rate for hepatitis A infections is 0.01-0.1% of patients. Older patients or those with previous damage, such as chronic hepatitis B or C, are mainly affected. In the over-50 age group, the mortality rate increases to 3%.

Chronic hepatitis A infections are generally not to be expected. Once the infection has been overcome, patients cannot become virus carriers and are no longer infectious as soon as the hepatitis A infection is completely cured. According to current knowledge (as of December 2019), once an infection has been overcome, lifelong immunity is guaranteed.

Prophylaxis

  • Vaccination : Vaccination against hepatitis A is an effective way to protect against this viral disease. People with an increased risk of infection in particular should consider vaccination in accordance with recommendations. The vaccination is indicated for, among others
    • People with an increased risk of infection
    • Persons with hemophilia requiring substitution therapy
    • Drug users
    • Residents and employees in healthcare or psychiatric facilities or
    • Persons with chronic liver disease or a chronic disease with liver involvement who are unable to produce HAV antibodies.
    • Healthcare workers, especially in pediatrics and infectious diseases.
    • Laboratory staff in high-risk areas who carry out stool tests, for example.
    • Sewerage and sewage treatment plant workers who have direct contact with sewage.
    • Travelers in regions with a high incidence of hepatitis A.

Full immunization requires an initial dose and two booster doses, the exact schedule of which depends on the manufacturer. The vaccine is an inactivated vaccine. Hepatitis A vaccination can be given alone, in combination with typhoid or in combination with hepatitis B. After complete immunization, no further booster is usually required, as vaccination protection lasts for around 25 to 30 years according to current knowledge (as of 2019). People in the healthcare sector who are exposed to hepatitis A sufferers should have their vaccination titre checked regularly, as there may be individual differences.

Post-exposure prophylaxis

Rapid action is required after contact with a person with hepatitis A, especially if someone has not been vaccinated. Carrying out a lockdown vaccination or post-exposure prophylaxis is crucial to prevent possible hepatitis A infection. However, it is important to note that even post-exposure immunization cannot eliminate the disease 100%. For this reason, those affected should take special hygienic measures in the first two weeks after exposure to protect those around them from possible infection. After a post-exposure vaccination, contact persons must be excluded from schools and other communal facilities for at least two weeks. If no post-exposure vaccination is given, the exclusion is extended to at least four weeks. A rapid and appropriate response to possible contact with hepatitis A is crucial to minimize the risk of infection and prevent the spread of the disease. Hygiene measures and compliance with official regulations play an important role in this process.

Hygiene measures

It is advisable that people who may be infected with hepatitis A follow special hygiene measures one to two weeks before symptoms appear. These include thorough hand hygiene and the use of a private toilet to minimize the spread of the virus. As soon as symptoms appear, infected persons should be isolated for up to two weeks after the first appearance of clinical symptoms, or up to one week after the onset of jaundice. Special occupational conditions apply to hepatitis A sufferers or persons suspected of having the disease. This applies in particular to activities in communal facilities and the food industry in order to contain the spread of the disease. Compliance with these measures is crucial to minimize the risk of further infection and protect public health.