Hepatitis A is a viral liver disease caused by the hepatitis A virus (HAV). Hepatitis A virus is an undeveloped RNA virus and is considered a picornavirus. Humans are the only natural host of this virus.⁽¹⁾ The hepatitis A virus is very stable and can remain present for several months in most environments. The virus, however, can be killed by high temperatures (above 85°) or by solutions such as chlorine or formalin.^(2-3)

Hepatitis A is contracted orally and is typically acquired by contact with human fecal waste, generally through consumption of contaminated food and/or water.⁽⁴⁾ Sources of contamination may include raw shellfish, fruits and vegetables, and ice.⁽⁵⁾

Hepatitis A replicates in the liver and can be found in the bloodstream within 10 to 12 days of exposure. The virus is excreted from the biliary system in the feces of a contaminated individual.⁽⁶⁾ An infected individual can spread hepatitis A to others for one to two weeks before becoming symptomatic.^(7-8) Virus excretion may persist longer in children than in adults, however, by the third week of illness, most infected individuals no longer excrete the virus in the stool.⁽⁹⁾

Symptoms of hepatitis A appear on average four weeks (two to seven weeks) after exposure. Symptoms often come on suddenly and include fatigue, abdominal and/or joint pain, loss of appetite, fever, nausea, jaundice, dark urine, clay-colored bowel movements, and diarrhea. Young children are often asymptomatic and show no clinical signs of infection.⁽¹⁰⁾ Most infected individuals recover completely within two months, but approximately 10 to 15 percent of infected individuals may have persistent symptoms for up to six months.⁽¹¹⁾

Hepatitis A infection does not cause chronic liver disease⁽¹²⁾ and people who recover from the disease develop lifelong immunity.⁽¹³⁾

Is hepatitis A contagious?

Hepatitis A is contagious and spreads from person to person through exposure to oral contact with the feces of an infected person.^{1 (14)} Infection can occur following exposure to water or food contaminated with the virus. Sources of contamination can include raw shellfish, vegetables, fruit and even contaminated ice.⁽¹⁵⁾ Transmission of the virus through blood is very rare.⁽¹⁶⁾ Hepatitis A thrives in areas without adequate sanitation and where personal hygiene habits are poor.⁽¹⁷⁾ Contaminated water sources can also be a source of transmission. Hepatitis A can infect drinking water through several sources, including malfunctioning sewer systems, pollution from stormwater runoff, and sewage overflows.⁽¹⁸⁾ Wells can also be contaminated if they are shallow or if floodwaters have submerged them for long periods of time.⁽¹⁹⁾

Hepatitis A is endemic in many areas of the world, including Africa, the Middle East, the Western Pacific, Asia, and Central and South America.⁽²⁰⁾ People traveling to developing countries with high or intermediate levels of hepatitis A are at increased risk of contracting the virus and developing the infection.⁽²¹⁾

Since 2016, several states have reported hepatitis A outbreaks linked primarily to people experiencing homelessness and among individuals who use drugs.⁽²²⁾ Between the end of 2016 and January 6, 2023, more than 44.700 cases were reported, resulting in 27.332 hospitalizations and 421 deaths.⁽²³⁾ It is believed that the increased number of hospitalizations and deaths that have occurred during this ongoing epidemic can be attributed to cofactors such as pre-existing health conditions, hepatitis B and C co-infections, age, and additional risk behaviors found in this particular population.⁽²⁴⁾