Hepatitis A

Hepatitis A

Basic facts

Hepatitis A is an inflammatory liver disease that can be mild or severe.

Transmission of the hepatitis A virus (HAV) occurs as a result of consuming contaminated food and water or through direct contact with an infected person.

Almost all patients with hepatitis A are completely cured and develop lifelong immunity. However, in very rare cases, infection with the hepatitis A virus can lead to fulminant hepatitis with a fatal outcome.

The risk of hepatitis A infection occurs in conditions of lack of safe water supply, in poor sanitary and hygienic conditions and in case of non-compliance with hygiene rules (for example, infection and contamination of hands).

There is a safe and effective vaccine to prevent hepatitis A.

Review

Hepatitis A is an inflammatory liver disease caused by the hepatitis A virus (HAV). The virus spreads mainly as a result of an uninfected (and unvaccinated) person consuming food or water contaminated with the feces of an infected person. This disease is closely related to poor water supply or food contamination, poor sanitary conditions, lack of personal hygiene and oral-anal sex.

Unlike hepatitis B and C, hepatitis A does not cause chronic liver disease, but can be accompanied by severe symptoms and sometimes fulminant (with acute liver failure), which often ends in death. According to WHO estimates, hepatitis A killed 7,134 people worldwide in 2016 (representing 0.5% of all deaths from viral hepatitis).

Hepatitis A is found worldwide and occurs both in isolated cases and in epidemics that tend to be cyclical. Epidemics caused by contamination of food or drinking water can be explosive, such as the 1988 epidemic in Shanghai, which affected approximately 300,000 people (1). Epidemics can be protracted and affect entire settlements for several months due to the transmission of infection from person to person. Hepatitis A virus persists for a long time in the environment and can remain viable even after food processing processes that are commonly used to control or inactivate bacterial pathogens.

Geographical distribution

Areas of spread of hepatitis A virus can be divided into areas with high, medium or low rates of infection. At the same time, the rate of infection is not always the same as morbidity, since the infection occurs with weak symptoms in young children.

In low- and middle-income countries with poor sanitation and poor hygiene practices, infection is widespread, and most children (90%) are infected with hepatitis A by the age of 10 years, often asymptomatically. infections (2). In high-income countries with good sanitation, infection rates are low. The disease can occur among adolescents and adults from high-risk groups, such as people who inject drugs, men who have sex with men, and people who visit areas with high hepatitis A endemicity, as well as among isolated groups population, such as closed religious groups. In the United States of America, significant outbreaks of hepatitis A have been reported among individuals without a fixed residence. In middle-income countries and areas with heterogeneous sanitary and hygienic conditions, a large proportion of the population does not tolerate infection in early childhood and reaches adulthood without developed immunity.

Transmission of infection

The main mechanism of transmission of the hepatitis A virus is fecal-oral, in which infection with the virus occurs as a result of consumption by an uninfected person of food or water contaminated with the feces of an infected person. At the household level, infection can occur when an infected person does not follow hand hygiene rules when preparing food for other family members. Outbreaks of waterborne diseases, although rare, are usually associated with consumption of sewage-contaminated or insufficiently treated water.

The virus can also be transmitted during close physical contact (for example, during oral-anal sex) with an infected person, while the virus is not transmitted during normal household contacts.

Symptoms

The duration of the incubation period of hepatitis A is usually 14-28 days.

Symptoms of hepatitis A can range from mild to severe and may include fever, malaise, loss of appetite, diarrhea, nausea, abdominal discomfort, dark urine, and jaundice (yellowing of the eyes and skin). The entire spectrum of symptoms is manifested in all infected people.

Clinical symptoms of the disease are observed more often in adults than in children. The prevalence of severe forms of the disease and mortality are higher among representatives of older age groups. In children under the age of 6, the infection usually proceeds with mild symptoms, and jaundice develops in only 10% of cases. In some patients, hepatitis A recurs, and a person who has just recovered becomes ill again in an acute form. After this, the disease usually ends with a full recovery.

Who is at risk?

Anyone who has not been vaccinated or has not contracted this disease in the past can become infected with the hepatitis A virus. In areas with wide circulation of the virus (high endemicity), most cases of hepatitis A infection occur in early childhood. Risk factors include:

unsatisfactory sanitary conditions;

lack of safe water supply;

the presence of an infected person among family members;

sexual contact with a person suffering from acute hepatitis A;

recreational use of psychoactive substances;

same-sex sexual contacts in men; and

travel to areas with high endemicity without prior immunization.

Diagnostics

The clinical picture of hepatitis A differs from other types of acute viral hepatitis. An accurate diagnosis is confirmed by a blood test for the presence of HGA-specific immunoglobulin M (IgM). In addition to this, diagnostics can be carried out by the polymerase chain reaction with reverse transcription (PCR-PCR), which allows the detection of hepatitis A virus RNA, which may require a referral to a specialized laboratory.

Treatment

There is no specific treatment for hepatitis A. The healing process can be slow and take several weeks or months. It is important to refrain from unjustified prescription of drugs that can negatively affect the liver, for example, acetaminophen, paracetamol.

In the absence of acute liver failure, hospitalization of patients is not required. Treatment is aimed at maintaining comfort and a balanced diet, including replenishing fluid losses caused by vomiting and diarrhea.

Prevention

The most effective means of combating hepatitis A are improving sanitation, increasing food safety, and expanding vaccination coverage.

The prevalence of hepatitis A can be reduced by the following measures:

ensuring sufficient supply of safe drinking water;

organization of proper wastewater disposal in settlements; and

observing personal hygiene rules, such as regular hand washing before eating and after using the toilet.

There are several injectable inactivated hepatitis A vaccines on the world market. They all provide a comparable level of protection against the virus and have similar side effects. None of the vaccines are licensed for children under one year of age. In China, an attenuated live vaccine is also used.

Activities of WHO

Global Health Sector Strategies for HIV, Viral Hepatitis and Sexually Transmitted Infections 2022–2030. (HSSZ) direct the health sector to implement strategically oriented measures to achieve the goals of eliminating AIDS, viral hepatitis (especially chronic hepatitis B and C), and sexually transmitted infections by 2030.

The GHS recommends general and disease-specific actions at the country level, as well as accompanying supporting actions by WHO and partners. They have been developed taking into account the epidemiological, technological and contextual changes that have taken place in the past years, stimulate the expansion of knowledge about various diseases and contribute to increasing opportunities to use innovations and new knowledge in order to effectively fight diseases. They are designed to expand the scope of prevention, diagnosis and treatment of viral hepatitis, paying particular attention to ensuring coverage of the most affected populations and groups at risk of these diseases, as well as closing gaps and inequalities. These strategies contribute to the achievement of synergistic effects within the framework of universal health coverage and primary health care and contribute to the achievement of the goals of the 2030 Agenda for Sustainable Development.

WHO organizes annual World Hepatitis Day events (as part of nine major annual health campaigns) to raise awareness and understanding of the problem of viral hepatitis. World Hepatitis Day 2023 is organized by WHO under the slogan "One Life - One Liver" to emphasize the importance of the liver for a healthy life and the need to scale up the prevention, diagnosis and treatment of viral hepatitis to prevent liver diseases and achieve the goal of eliminating hepatitis by 2030 p.

 

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