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 in California and four other states affected a large number of homeless persons and resulted in many deaths

• HAV has been described as a reemerging food-borne public health threat in Europe

• 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

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, Middle East respiratory syndrome virus, yellow fever virus, influenza virus, Ebola virus, and others

• Spirochetal diseases, such as leptospirosis and secondary syphilis

• Brucellosis

• Rickettsial diseases, ...