Overview
Hepatitis A is an inflammation of the liver caused by the hepatitis A virus (HAV). The virus is primarily spread when an uninfected (and unvaccinated) person ingests food or water that is contaminated with the faeces of an infected person. The disease is closely associated with unsafe water or food, inadequate sanitation, poor personal hygiene and oral-anal sex.
Unlike hepatitis B and C, hepatitis A does not cause chronic liver disease but it can cause debilitating symptoms and rarely fulminant hepatitis (acute liver failure), which is often fatal. WHO estimates that in 2016, 7134 persons died from hepatitis A worldwide (accounting for 0.5% of the mortality due to viral hepatitis).
Hepatitis A occurs sporadically and in epidemics worldwide, with a tendency for cyclic recurrences. Epidemics related to contaminated food or water can erupt explosively, such as the epidemic in Shanghai in 1988 that affected about 300 000 people (1). They can also be prolonged, affecting communities for months through person-to-person transmission. Hepatitis A viruses persist in the environment and can withstand food production processes routinely used to inactivate or control bacterial pathogens.
Geographical distribution
Geographical distribution areas can be characterized as having high, intermediate or low levels of hepatitis A virus infection. However, infection does not always mean disease because infected young children do not experience any noticeable symptoms.
Infection is common in low- and middle-income countries with poor sanitary conditions and hygienic practices, and most children (90%) have been infected with the hepatitis A virus before the age of 10 years, most often without symptoms (2). Infection rates are low in high-income countries with good sanitary and hygienic conditions. Disease may occur among adolescents and adults in high-risk groups, such as persons who inject drugs (PWID), men who have sex with men (MSM), people travelling to areas of high endemicity and in isolated populations, such as closed religious groups. In the United States of America, large outbreaks have been reported among persons experiencing homelessness. In middle-income countries and regions where sanitary conditions are variable, children often escape infection in early childhood and reach adulthood without immunity.
Transmission
The hepatitis A virus is transmitted primarily by the faecal-oral route; that is when an uninfected person ingests food or water that has been contaminated with the faeces of an infected person. In families, this may happen though dirty hands when an infected person prepares food for family members. Waterborne outbreaks, though infrequent, are usually associated with sewage-contaminated or inadequately treated water.
The virus can also be transmitted through close physical contact (such as oral-anal sex) with an infectious person, although casual contact among people does not spread the virus.
Symptoms
The incubation period of hepatitis A is usually 14–28 days.
Symptoms of hepatitis A range from mild to severe and can include fever, malaise, loss of appetite, diarrhoea, nausea, abdominal discomfort, dark-coloured urine and jaundice (a yellowing of the eyes and skin). Not everyone who is infected will have all the symptoms.
Adults have signs and symptoms of illness more often than children. The severity of disease and fatal outcomes are higher in older age groups. Infected children under 6 years of age do not usually experience noticeable symptoms, and only 10% develop jaundice. Hepatitis A sometimes relapses, meaning the person who just recovered falls sick again with another acute episode. This is normally followed by recovery.
Who is at risk?
Anyone who has not been vaccinated or previously infected can get infected with the hepatitis A virus. In areas where the virus is widespread (high endemicity), most hepatitis A infections occur during early childhood. Risk factors include:
- poor sanitation;
- lack of safe water;
- living in a household with an infected person;
- being a sexual partner of someone with acute hepatitis A infection;
- use of recreational drugs;
- sex between men; and
- travelling to areas of high endemicity without being immunized.
Diagnosis
Cases of hepatitis A are not clinically distinguishable from other types of acute viral hepatitis. Specific diagnosis is made by the detection of HAV-specific immunoglobulin G (IgM) antibodies in the blood. Additional tests include reverse transcriptase polymerase chain reaction (RT-PCR) to detect the hepatitis A virus RNA and may require specialized laboratory facilities.
Treatment
There is no specific treatment for hepatitis A. Recovery from symptoms following infection may be slow and can take several weeks or months. It is important to avoid unnecessary medications that can adversely affect the liver, e.g. acetaminophen, paracetamol.
Hospitalization is unnecessary in the absence of acute liver failure. Therapy is aimed at maintaining comfort and adequate nutritional balance, including replacement of fluids that are lost from vomiting and diarrhoea.
Prevention
Improved sanitation, food safety and immunization are the most effective ways to combat hepatitis A.
The spread of hepatitis A can be reduced by:
- adequate supplies of safe drinking water;
- proper disposal of sewage within communities; and
- personal hygiene practices such as regular handwashing before meals and after going to the bathroom.
Several injectable inactivated hepatitis A vaccines are available internationally. All provide similar protection from the virus and have comparable side effects. No vaccine is licensed for children younger than 1 year of age. In China, a live attenuated vaccine is also available.
WHO response
Global health sector strategies on, respectively, HIV, viral hepatitis, and sexually transmitted infections for the period 2022–2030 (GHSSs) guide the health sector in implementing strategically focused responses to achieve the goals of ending AIDS, viral hepatitis (especially chronic hepatitis B and C) and sexually transmitted infections by 2030.
The GHSS recommend shared and disease-specific country actions supported by actions by WHO and partners. They consider the epidemiological, technological, and contextual shifts of previous years, foster learnings across the disease areas, and create opportunities to leverage innovations and new knowledge for effective responses to the diseases. They call to scale up prevention, testing and treatment of viral hepatitis with a focus to reach populations and communities most affected and at risk for each disease, as well as addressing gaps and inequities. They promote synergies under a universal health coverage and primary health care framework and contribute to achieving the goals of the 2030 Agenda for Sustainable Development.
WHO organizes annual World Hepatitis Day campaigns (as 1 of its 9 flagship annual health campaigns) to increase awareness and understanding of viral hepatitis. For World Hepatitis Day 2023, WHO focuses on the theme “One life, one liver” to illustrate the importance of the liver for a healthy life and the need to scale up viral hepatitis prevention, testing and treatment to prevent liver diseases and achieve the 2030 hepatitis elimination target.