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Hepatitis A virus infection in adults: An overview

Michelle Lai, MD, MPH
Sanjiv Chopra, MD, MACP
Section Editor
Martin S Hirsch, MD
Deputy Editor
Elinor L Baron, MD, DTMH


Hepatitis A infection is caused by the hepatitis A virus (HAV). Humans are the only known reservoir. HAV infection is usually a self-limited illness that does not become chronic. Fulminant hepatic failure occurs in less than 1 percent of cases. Infection confers lifelong immunity and is preventable via vaccination.

HAV is a member of the genus Hepatovirus in the family Picornaviridae. Two clinical forms of hepatitis were recognized in 1947 and designated hepatitis A and hepatitis B [1]; subsequently, the virus that causes hepatitis A was identified in 1973 [2]. Other terms previously used for hepatitis A virus infection include epidemic jaundice, acute catarrhal jaundice, and campaign jaundice.

The epidemiology, clinical manifestations, diagnosis, and treatment of HAV infection in adults are reviewed here. Issues related to HAV vaccination are presented separately, as are issues related to HAV in children and pregnant women. (See "Hepatitis A virus infection: Prevention" and "Overview of hepatitis A virus infection in children" and "Intercurrent hepatobiliary disease during pregnancy", section on 'Hepatitis A'.)


Hepatitis A virus (HAV) infection occurs worldwide. Globally, an estimated 1.4 million cases occur each year [3]. HAV is usually transmitted by the fecal-oral route (either via person-to-person contact or consumption of contaminated food or water). Risk factors for HAV transmission include residence in or travel to areas to poor sanitation, household or sexual contact with another person with hepatitis A, homosexual activity in men, exposure to daycare centers, exposure to residential institutions, and illicit drug use (table 1) [4-6]. Bloodborne transmission can occur but is uncommon [7]. Maternal-fetal transmission has not been described.

The incidence of HAV has declined substantially since implementation of vaccination among children. In the United States, since vaccination was recommended for individuals at increased risk for infection (in 1996), children living in states with the highest incidence of HAV (in 1999) and for all infants (in 2006), the incidence of acute hepatitis A has declined from 6 to 0.4 cases per 100,000 between 1999 and 2014; an estimated 2500 cases of hepatitis A occurred in 2014 (figure 1 and figure 2) [4,8-14]. Similarly, in China, the incidence among individuals age ≤19 years in one province declined to a historically low rate in 2014, while the highest incidence rate was observed in those aged ≥20 years [15]. In addition, improvement of living conditions in developing countries has been associated with fewer child infections, leading to a larger population of adults who lack protective antibodies and are at risk for outbreaks (figure 3) [15].


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Literature review current through: Jul 2017. | This topic last updated: Oct 17, 2016.
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