Hepatitis A virus (HAV) is a non‑enveloped, single‑stranded RNA virus in the family Picornaviridae that causes acute viral hepatitis in humans. It spreads primarily via the fecal‑oral route through person‑to‑person contact or ingestion of contaminated food or water.
Virology and Epidemiology
HAV is classified in the genus Hepatovirus and has a positive‑sense RNA genome of about 7.5 kb enclosed within a small (~30 nm) icosahedral capsid. Lacking an envelope, the virus is resistant to environmental stresses such as heat and mild detergents and can remain infectious on surfaces for prolonged periods. HAV replicates in the liver, where newly synthesized virions are excreted into bile and reach the intestine. Large quantities of virus are shed in stool one to two weeks before symptom onset, facilitating transmission through contaminated hands, food and water. Person‑to‑person spread is most common in areas with poor sanitation and crowded living conditions. The incubation period averages 28 days (range 15‑50 days). Globally, HAV is endemic in regions with inadequate sanitation; in high‑income countries most cases occur in travelers, men who have sex with men and people who use injection drugs. Unlike hepatitis B or C viruses, HAV does not establish chronic infection.
Clinical Features and Prevention
Clinical illness ranges from asymptomatic infection, especially in young children, to fulminant hepatitis in older adults or those with underlying liver disease. Typical symptoms include fever, anorexia, nausea, abdominal discomfort and jaundice. Extrahepatic manifestations are uncommon. Most patients recover fully within weeks to months, and lifelong immunity follows infection. There is no specific antiviral therapy; management is supportive with attention to hydration and nutrition. Vaccination with inactivated HAV vaccine induces protective antibodies and is recommended for travelers to endemic areas, children in high‑risk populations and individuals at occupational risk. Passive immunoglobulin prophylaxis can protect contacts after exposure. Prevention depends on improved sanitation, safe water supplies, good hand hygiene and vaccination. Outbreaks linked to contaminated food items such as shellfish and frozen berries highlight the need for vigilant food safety measures. Hepatitis A virus remains an important cause of acute viral hepatitis worldwide. Effective vaccines and sanitation measures have reduced incidence in many regions, but sporadic outbreaks continue to occur, emphasizing the need for ongoing public health efforts. Related Terms: Hepatitis B virus, Hepatitis C virus, Picornavirus, Enterovirus, Fecal‑oral transmission