Hepatitis A

Key Features

Essentials of Diagnosis

• Prodrome of anorexia, nausea, vomiting, malaise, aversion to smoking

• Fever, enlarged and tender liver, jaundice

• Normal to low white blood cell count; markedly elevated aminotransferases

General Considerations

• Transmission of hepatitis A virus (HAV) is by the fecal-oral route by either person-to-person contact or ingestion of contaminated food or water

• The incubation period averages 30 days

• HAV is excreted in feces for up to 2 weeks before the clinical illness and rarely persists in feces after the first week of illness

• There is no chronic carrier state

Demographics

• Globally, 15 million people are infected with HAV annually

• HAV spread is favored by crowding and poor sanitation

• HAV infection is hyperendemic in developing countries

• Common source outbreaks result from contaminated water or food

• In 2017, an outbreak beginning in California and extending to 33 other states affected a large number of homeless persons and resulted in many deaths

• Outbreaks have been reported among injection drug users

• Since introduction of HAV vaccine in the United States in 1995, the incidence rate of HAV infection has declined from 14 to 0.4 per 100,000 population

• Over 80% of persons aged 20–60 years in the United States are still susceptible to HAV, and vulnerable populations are especially at risk

• The highest incidence rate (2.1 per 100,00) is in adults aged 30–39

Clinical Findings

Symptoms and Signs

• Onset may be abrupt or insidious

• Malaise, myalgia, arthralgia, easy fatigability, upper respiratory symptoms, and anorexia

• A distaste for smoking, paralleling anorexia, may occur early

• Nausea and vomiting are frequent, and diarrhea or constipation may occur

• Defervescence and a fall in pulse rate often coincide with the onset of jaundice

• Abdominal pain

  • Usually mild and constant in the right upper quadrant or epigastrium

  • Often aggravated by jarring or exertion

  • Rarely severe enough to simulate cholecystitis

• Jaundice

  • Never develops in many patients

  • Occurs after 5–10 days but may appear at the same time as the initial symptoms

  • With its onset, prodromal symptoms often worsen, followed by progressive clinical improvement

  • Stools may be acholic

• Hepatomegaly—rarely marked—is present in over 50% of cases; liver tenderness is usually present

• Splenomegaly occurs in 15% of patients

• Soft, enlarged lymph nodes—especially in the cervical or epitrochlear areas—may occur

• The acute illness usually subsides over 2–3 weeks

• Complete clinical and laboratory recovery by 9 weeks

• Clinical, biochemical, and serologic recovery may be followed by one or two relapses, but recovery is the rule

• A protracted course has been reported to be associated with HLA DRB1*1301

Differential Diagnosis

• Other viruses that cause hepatitis, particularly hepatitis B and C viruses, as well as Epstein-Barr (infectious mononucleosis) virus, cytomegalovirus, herpes simplex virus, ...