Hepatitis B, Acute

Key Features

Essentials of Diagnosis

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

• Fever, tender hepatomegaly, jaundice

• Markedly elevated serum aminotransferases early in the course

• Normal to low white blood cell count

• Liver biopsy shows hepatocellular necrosis and mononuclear infiltrate but is rarely indicated

General Considerations

• Hepatitis B virus (HBV) contains an inner core protein (hepatitis B core antigen, HBcAg) and outer surface coat (hepatitis B surface antigen, HBsAg)

• The incubation period is 6 weeks to 6 months (average 3 months)

• The onset of HBV is more insidious and the aminotransferase levels higher on average than in hepatitis A virus (HAV) infection

• 10 genotypes of HBV (A–J) have been identified

Demographics

• Incidence has decreased from 8.5 to 1.5 cases per 100,000 population since the 1990s

• HBV is usually transmitted by

  • Infected blood or blood products

  • Sexual contact

• It is also present in saliva, semen, and vaginal secretions

• About 7% of HIV-infected persons are coinfected with HBV

• HBsAg-positive mothers may transmit HBV to the neonate at delivery

• The risk of chronic infection in the infant approaches 90% if the mother is HBeAg positive

• HBV is prevalent in men who have sex with men and injection drug users, but most cases result from heterosexual transmission

• Other groups at high risk include

  • Patients and staff at hemodialysis centers

  • Physicians, dentists, and nurses

  • Personnel working in clinical and pathology laboratories and blood banks

• The risk of HBV infection from a blood transfusion in the United States is no higher than 1 in 350,000 units transfused

• Screening for HBV infection is recommended for high-risk groups by the US Preventive Services Task Force

Clinical Findings

Symptoms and Signs

• Onset may be abrupt or insidious

• Malaise, myalgia, arthralgia, fatigability, upper respiratory symptoms, anorexia, and a distaste for smoking

• Nausea and vomiting, diarrhea or constipation

• Low-grade fever is generally present; serum sickness may occur

• Abdominal pain is usually mild and constant in the right upper quadrant or epigastrium

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

• Jaundice occurs after 5–10 days but may appear at the same time as the initial symptoms; in many patients, it never develops

• Often worsening of the prodromal symptoms, followed by progressive clinical improvement

• Stools may be acholic

• The acute illness usually subsides over 2–3 weeks

• In most patients, there is complete clinical and laboratory recovery by 16 weeks

• In 5–10% of cases, the course may be more protracted, but acute liver failure develops in < 1%

• Hepatitis B may become chronic

Differential Diagnosis

• Acute and chronic hepatitis ACDE

• The TT virus (TTV) is found in up to 7.5% of blood donors and is ...