[2] When symptoms occur, they typically last eight weeks and may include nausea, vomiting, diarrhea, jaundice, fever, and abdominal pain.

[11][12][13] [1][4][needs update] Some countries recommend it routinely for children and those at higher risk who have not previously been vaccinated.

[14] It often occurs in outbreaks in moderately developed countries where children are not exposed when young and vaccination is not widespread.

[34] The mean age of genotypes III and IIIA strains has been estimated to be 592 and 202 years, respectively.

[34] Hepatovirus A is a picornavirus; it is not enveloped and contains a positive-sense, single-strand of RNA packaged in a protein shell.

[36] In the region that codes for the HAV capsid, highly conserved clusters of rare codons restrict antigenic variability.

HAV is excreted in large numbers about 11 days prior to the appearance of symptoms or anti-HAV IgM antibodies in the blood.

[citation needed] Within the liver hepatocytes, the RNA genome is released from the protein coat and is translated by the cell's own ribosomes.

[39] The requirement for this factor results in an inability to shut down host protein synthesis, unlike other picornaviruses.

The virus must then inefficiently compete for the cellular translational machinery, which may explain its poor growth in cell culture.

Aragonès et al. (2010) theorize that the virus has evolved a naturally highly deoptimized codon usage with respect to that of its cellular host in order to negatively influence viral protein translation kinetics and allow time for capsid proteins to fold optimally.

[39] No apparent virus-mediated cytotoxicity occurs, presumably because of the virus' own requirement for an intact eIF4G, and liver pathology is likely immune-mediated.

The virus primarily spreads by the fecal–oral route,[3] and infections often occur in conditions of poor sanitation and overcrowding.

Food-borne outbreaks are common,[40] and ingestion of shellfish cultivated in polluted water is associated with a high risk of infection.

The virus is resistant to detergent, acid (pH 1), solvents (e.g., ether, chloroform), drying, and temperatures up to 60 °C.

In developing countries, and in regions with poor hygiene standards, the rates of infection with this virus are high[43] and the illness is usually contracted in early childhood.

As incomes rise and access to clean water increases, the incidence of HAV decreases.

Although HAV is excreted in the feces towards the end of the incubation period, specific diagnosis is made by the detection of HAV-specific IgM antibodies in the blood.

The presence of IgG antibodies in the blood means the acute stage of the illness has passed and the person is immune to further infection.

[45] During the acute stage of the infection, the liver enzyme alanine transferase (ALT) is present in the blood at levels much higher than is normal.

[46] Hepatovirus A is present in the blood (viremia) and feces of infected people up to 2 weeks before clinical illness develops.

Therapy is aimed at maintaining comfort and adequate nutritional balance, including replacement of fluids lost from vomiting and diarrhea.

[40] Globally, symptomatic HAV infections are believed to occur in around 1.4 million people a year.

[64][65] In 1988, more than 300,000 people in Shanghai, China, were infected with HAV after eating clams (Anadara subcrenata) from a contaminated river.

[66][67] In April 2016, frozen berries sold by Costco were once again the subject of a recall, after at least 13 people in Canada were infected with HAV, three of whom were hospitalized.

[68] In Australia in February 2015, a recall of frozen berries was issued after at least 19 people contracted the illness following their consumption of the product.

[69] In 2017, California (particularly around San Diego), Michigan, and Utah reported outbreaks of hepatitis A that have led to over 800 hospitalizations and 40 deaths.