Hepatitis A

The key points:

• Hepatitis A is an infectious liver disease caused by the hepatitis A virus (HAV), present in countries with low hygiene standards.
• It is transmitted through fecal-oral contamination, via contaminated water or food, or through direct contact with an infected person.
• There is no chronic form, no treatment. Recovery is spontaneous and confers lifelong protection.
• There is a safe and highly effective vaccine.

What is hepatitis A?

The hepatitis A Hepatitis A is an acute infectious disease of the liver caused by a virus: the hepatitis A virus (HAV). It differs from hepatitis B or C primarily in its modes of transmission and the fact that the disease never becomes chronic. Fecal-oral transmission is by far the most common. Transmission can occur indirectly through the ingestion of water or food contaminated with infected feces (or contaminated by a food preparation worker with soiled hands), or directly through contact with an infected person (within families or communities, for example). It frequently occurs in contexts where water sanitation is inadequate and basic hygiene measures, such as handwashing, are not observed. Among men who have sex with men (MSM), digital anal or oral anal sex practices are thought to facilitate transmission of the disease.

Hepatitis A worldwide

Hepatitis A is present worldwide, but the risk of infection is higher in countries with poor hygiene. Depending on the risk of HAV transmission, four types of geographical areas are distinguished:

• areas of high endemicity: where the risk of contracting hepatitis A is very high and where the indigenous population is contaminated very early in life due to an insufficient level of collective hygiene (Africa, Middle East, Indian subcontinent, China, Central and South America);
• areas of moderate endemicity: They are scattered across all continents;
• areas of low endemicity: Most industrialized countries, namely North America, Northern Europe, Japan, and Australia, fall into this category. Virus circulation has become very rare, but has not been eliminated. Outbreaks from a common source can occur (for example, linked to shellfish consumption). France is a country with low endemicity;
• areas of very low endemicity: where the risk of local transmission has become virtually nil. The Scandinavian countries have eliminated hepatitis A, and their inhabitants are extremely vulnerable to this disease when travelling abroad.

Outbreaks in Northern European countries can also occur when unvaccinated children are infected during family visits to tropical and subtropical countries and transmit the virus to families or care facilities upon their return.

Symptoms of hepatitis A

Approximately 2 to 4 weeks after infection, the disease manifests with fever, headache, fatigue, loss of appetite, liver pain, nausea, and jaundice (yellowing of the skin and eyes, pale stools, and dark urine). Most symptoms disappear within a few weeks or months, although fatigue may persist longer. There is no chronic form of the disease; once the infection has cleared, immunity lasts a lifetime. In children under 6 years of age, the infection is usually asymptomatic or only mildly symptomatic. Beyond this age, the severity of the disease increases with age (or in cases of pre-existing liver disease), with the possibility of progression to fulminant hepatitis (fatality 0,1%–0,3%; 1,8% among those over 50), the prognosis of which remains very poor despite the possibility of emergency liver transplantation.

Diagnosis of hepatitis A

From a biological standpoint, an elevation of liver enzymes (ALT and AST transaminases) is observed, indicating liver damage. diagnosis of hepatitis A This method relies on the detection of specific anti-HAV IgM antibodies using the ELISA technique. IgM antibodies appear with the ALT peak, at the beginning of the icteric phase, and disappear within a few months. Anti-HAV IgG antibodies, present from the acute phase of hepatitis, generally persist throughout life. Their detection is useful in sero-epidemiological surveys and for pre-vaccination screening.

Treatment of hepatitis A

There is no specific treatment for hepatitis A. Management consists solely of relieving symptoms. Vaccination up to 7 days after contact with the virus can prevent the onset of the disease or lessen its severity.

Prevention of hepatitis A

La prevention of hepatitis A It relies on adherence to hygiene and dietary rules (regular handwashing, consumption of safe drinking water and food) and vaccination. There is a safe and highly effective vaccine consisting of two injections spaced at least 6 months apart. It offers lifelong protection after the second dose. The hepatitis A vaccine can also be administered in combination with the vaccine against...Hepatitis B (3 doses required if administered to individuals aged 16 years and older). In the general population, hepatitis A vaccination is recommended for:

• young people accommodated in establishments for disabled children and youth;
• people with cystic fibrosis;
• people with liver diseases that can become chronic, for example those caused by hepatitis B and C viruses or excessive alcohol consumption;
• children, from the age of 1 year, born into families where at least one member comes from a country where hepatitis A is widespread and who are likely to stay there;
• men having sex with other men.

There are also vaccination recommendations for professionals at risk of infection:

• people taking care of children who have not yet reached the age of toilet training (nursery staff, childminders, etc.);
• staff of collective care facilities for disabled people;
• professionals involved in food preparation in institutional catering (canteens);
• people in charge of wastewater and sewage treatment.
• The military

For travelers, vaccination is recommended from the age of 1 year for all travelers planning to stay in a country with low hygiene standards, regardless of the conditions of their stay. A serological test prior to vaccination (detection of total anti-HAV antibodies or IgG) is relevant for individuals with a history of jaundice, those who spent a prolonged period or their childhood in an endemic area, or those born before 1945. The presence of anti-HAV antibodies (IgG) indicates prior immunity and does not warrant the administration of vaccine doses.