Acute hepatitis A

Acute hepatitis A is an infectious liver disease caused by Hepatitis A virus (HAV), a non-enveloped, positive-sense single-stranded RNA virus classified in the order Picornavirales, family Picornaviridae, genus Hepatovirus. The virus exhibits one serotype but exists across six genotypes, including three human and three simian variants, with genotype I being the most commonly isolated in human infections. HAV is transmitted via the fecal-oral route and represents one of five identified hepatitis viruses affecting humans.

Clinical presentation of hepatitis A varies substantially by age, with many infections, particularly in young children, producing few or no symptoms. When symptoms manifest, they typically appear two to six weeks following exposure and may include nausea, vomiting, diarrhea, jaundice, fever, and abdominal pain, with the symptomatic phase lasting approximately eight weeks. Approximately 10-15% of patients experience a recurrence of symptoms during the six months following initial infection. Extrahepatic manifestations, though uncommon, may include joint pains, red cell aplasia, pancreatitis, and generalized lymphadenopathy. Acute liver failure occurs rarely but is more frequent in elderly populations. Diagnosis requires specific blood testing, as clinical features overlap with other conditions.

Source-backed detail on geographic distribution, outbreak patterns, and surveillance burden is not yet available from the provided sources. The epidemiology is characterized by age-dependent symptomatic risk, with over 80% of adults developing symptoms compatible with acute viral hepatitis while the majority of children experience asymptomatic or unrecognized infections. Children, despite often lacking symptoms, remain capable of transmitting the infection to others.

Hepatitis A is predominantly a foodborne illness transmitted through ingestion of food or water contaminated with infected feces. Undercooked or raw shellfish represent relatively common vehicles for transmission. The virus may also spread through close contact with an infectious person, including household transmission or care-related exposure.

Older adults face elevated risk for severe outcomes, particularly acute liver failure, which occurs more frequently in this population compared to younger age groups. Children represent a significant transmission reservoir despite often experiencing asymptomatic infection, facilitating community spread. Individuals consuming undercooked shellfish or exposed to contaminated water sources face elevated exposure risk.

Prevention of hepatitis A is effectively achieved through vaccination, which provides protective immunity. Some national immunization programs routinely recommend hepatitis A vaccination for children and for individuals at higher risk who have not been previously vaccinated. The vaccine has demonstrated efficacy in preventing infection in exposed populations.

Surveillance for hepatitis A should account for the substantial proportion of asymptomatic infections, particularly in pediatric populations, which may underestimate true community transmission. Blood testing is required for definitive diagnosis, as clinical presentation overlaps with other acute viral syndromes and influenza-like illnesses. The potential for symptom recurrence within six months of initial infection should be considered when interpreting case timelines. Extrahepatic complications, while uncommon, may present as initial manifestations and should prompt hepatitis A testing in appropriate epidemiological contexts.

1. 1 Wikidata. Acute hepatitis associated with the Chinese herbal product jin bu huan.
2. 2 Wikipedia. Hepatitis A - Wikipedia.

ICD-10

B15

ICD-11

1E50.0

Total cases

0

Peak month

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Coverage

0 reporting countries · —