Hepatitis A virus infection
Hepatitis A virus is a fecal-oral RNA virus that causes acute, host-immune-mediated hepatitis with a prodrome followed by jaundice, aminotransferases often exceeding 1,000 U/L, and full recovery in at least 90% of patients within 3 to 6 months. Diagnosis rests on HAV IgM, treatment is supportive, and prevention centers on a 2-dose inactivated vaccine plus prompt postexposure prophylaxis.
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What this article covers
- Overview
Hepatitis A virus (HAV) is a fecal-oral RNA virus that causes acute hepatitis mediated by the host immune response, not by direct viral cytotoxicity.
- Epidemiology
Incidence declined dramatically after introduction of universal childhood HAV vaccination, but rates have recently increased among unvaccinated people, especially those reporting homelessness or drug use.
- Risk factors
International travel to an HAV-endemic region.
- Pathophysiology
Liver injury is host-immune-mediated, not directly cytopathic: cytotoxic T-cell responses against HAV-infected hepatocytes drive the hepatocellular injury and resulting acute hepatitis, rather than the virus itself damaging cells.
- Clinical features
A prodrome of malaise, nausea, vomiting, fever, and right-upper-quadrant pain begins the illness, typically about 1 week before jaundice and hepatomegaly appear.
- Differential diagnosis
Hepatitis B virus infection: bloodborne or perinatal transmission, confirmed by HBsAg positivity, with potential for chronicity, unlike the fecal-oral, always self-limited course of HAV; see hepatitis B virus infection.
- Diagnosis
Acute hepatitis A is confirmed by a positive HAV IgM antibody, obtained in any patient with an acute hepatitis picture (jaundice, right-upper-quadrant pain, marked aminotransferase elevation) and a…
- Management
Initially, for uncomplicated acute hepatitis A, treatment is supportive: rest, adequate hydration, and avoidance of hepatotoxic substances (alcohol, unnecessary or hepatotoxic medications) for the…
- Complications
Acute liver failure: encephalopathy plus coagulopathy within 26 weeks of jaundice onset; rare with HAV but carries increased mortality in patients with pre-existing chronic liver disease, and mandates immediate transplant-center referral.
- Prognosis
Excellent overall: at least 90% of patients recover fully within 3 to 6 months of infection, with no risk of chronic hepatitis.
- Prevention
Hepatitis A vaccination is the primary preventive measure: standard 2-dose inactivated vaccine series given at 0 and 6 to 18 months for nonimmune persons at risk, including international travelers…
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