Hepatitis A virus infection
The typical incubation time is 28 days (with a range of 15-50 days). In young children (younger than 5 years), most infections are asymptomatic, whereas in older children and adults, icteric infections are almost as common as anicteric forms. Symptomatic patients infected with hepatitis A experience a constellation of symptoms, including fever, fatigue, anorexia, abdominal pain, nausea, vomiting, diarrhea, pruritus (due to hyperbilirubinemia), and/or jaundice (typically preceded by onset of dark-colored urine). Physical examination often reveals hepatosplenomegaly. Laboratory findings typically include elevated transaminases and bilirubin. An evanescent rash and/or arthralgias may be seen in 1 in 10 cases. Other rare extrahepatic manifestations of hepatitis A include hemolytic or aplastic anemia, acalculous cholecystitis, myocarditis, toxic epidermal necrolysis, glomerulonephritis, and cutaneous vasculitis.
Hepatitis A is usually a self-limited disease that does not lead to chronic infection or chronic liver disease. However, 10%-15% of patients can experience transient relapses of symptoms within 6 months following the initial hepatitis A episode. Fulminant hepatitis A, with a case fatality rate of approximately 0.5%, can lead to acute liver failure and may require emergent liver transplantation.
Pediatric patient considerations: Most pediatric hepatitis A infections are asymptomatic or clinically unrecognized. Hepatitis A causes symptomatic illness in only 30% of adolescents and children compared with 70% of adults.
Immunocompromised patient considerations: Patients with underlying chronic liver disease, including chronic hepatitis B or hepatitis C, are at increased risk of morbidity and mortality due to acute hepatitis A. Those who are at increased risk for severe disease include individuals with chronic liver disease and individuals with HIV.
Among pregnant individuals, there is no evidence to suggest that acute hepatitis A is associated with an increased case fatality rate, although it is associated with increased risk of preterm labor and gestational complications.
B15.9 – Hepatitis A without hepatic coma
40468003 – Viral hepatitis, type A
Differential Diagnosis & Pitfalls
- Drug-induced hepatotoxicity (eg, acetaminophen) – Consider relevant exposure history.
- Viral hepatitides (hepatitis B, C, D, and E viruses, cytomegalovirus, Epstein-Barr virus [see, eg, mononucleosis], adenovirus, herpes simplex virus, yellow fever virus) – Consider relevant clinical findings and epidemiological history.
- Syphilitic hepatitis (uncommon presentation of secondary syphilis)
- Acute toxoplasmosis
- Fatty liver of pregnancy – Consider clinical context.
- Toxin exposure (eg, hydrocarbons, halothane) – Review exposure history.
- Bacterial infections (relapsing fever [tick-borne], leptospirosis, ehrlichiosis, Rocky Mountain spotted fever) – Consider relevant exposure history.
- Acute circulatory collapse and hypoperfusion (ie, "shock liver") due to cardiovascular and/or acute bacterial sepsis – Should be considered in appropriate clinical context.