Viral Hepatitis

Basics

Description

  • Viral hepatitis is defined as a systemic viral infection, in which the predominant manifestation is that of hepatic injury and dysfunction.
  • It is primarily caused by hepatotropic viruses, which include hepatitis A to E.
  • 10% of cases are caused by other viruses, such as Epstein-Barr virus (EBV), cytomegalovirus (CMV), herpes simplex virus (HSV), varicella-zoster virus (VZV), rubella, parvovirus, adenovirus, enteroviruses, and others.

Epidemiology

Incidence

  • Hepatitis A: ~2,500 cases per year in the United States
  • Hepatitis B: 140,000 to 320,000 infections per year worldwide; ~20,000 U.S. cases per year
  • Hepatitis C: 30,000 infections per year in the United States
  • Hepatitis E: common in poorly developed countries but rare in the United States

Prevalence

  • Hepatitis B: United States has a low prevalence with <1% of the population infected; higher rates in certain subgroups such as immigrants from endemic areas, men who have sex with men, and parenteral drug users
  • Hepatitis C: United States has prevalence of 1.8%, representing ~3.9 million people (85% chronically infected).

Risk Factors

  • Hepatitis A (transmission: fecal–oral)
    • Day care attendance, household exposure, travel to endemic areas, men who have sex with men
    • Maximum infectivity 2 weeks before jaundice
  • Hepatitis B and C (transmission: blood, body fluids, and sexual contact)
    • Recipients of blood or blood products
    • IV drug users
    • Multiple sexual partners
    • Men who have sex with men
    • Body piercing and tattoos
    • HIV-positive status
    • Infants born to a mother with hepatitis B or C
    • Household contacts with hepatitis B or C

General Prevention

  • Good sanitation, hygiene, vaccination, screening blood products, condom use, safe disposal of needles
  • Hepatitis A
    • Vaccination of all children between the ages of 1 and 18 years, especially those travelling to endemic regions or those with liver disease
    • Vaccine (Havrix, Vaqta): 0.5-mL dose IM and second dose 6 to 12 months later
    • Prior to travel to an endemic region, immune globulin 0.02 mL/kg should be given to children <1 year of age and considered for children who are immunocompromised or have liver disease.
    • Infected patients should avoid return to day care center for 2 weeks after illness subsides.
    • Postexposure prophylaxis for healthy children >1 year of age: hepatitis A vaccine
    • Postexposure prophylaxis for <1 year of age, immunocompromised individuals or patients with chronic liver disease: immune globulin 0.02 mL/kg IM
  • Hepatitis B
    • Screen all pregnant women.
    • Hepatitis B vaccine to all infants at birth; complete 3-vaccine series 0.5-mL dose IM during infancy.
    • Vaccine and hepatitis B immunoglobulin (HBIG) to high-risk infants
    • Mother’s with high viral loads or previous vertical transmission should consult a high-risk obstetrician and hepatitis B expert at least 3 to 6 months prior to delivery of another infant.
  • Hepatitis C
    • Elective C-section has not been shown to reduce vertical transmission.
    • During vaginal delivery, avoid fetal scalp monitoring and prolonged rupture of membranes >8 hours.
    • Avoid sharing of toothbrushes, nail clippers, and razors.
    • Breastfeeding is contraindicated only if mother has active bleeding from nipples.

Pathophysiology

  • Acute viral hepatitis tends to affect the liver parenchyma, whereas chronic viral hepatitis affects portal and periportal areas.
  • Chronic viral hepatitis (B or C) is defined by continuing viral replication and inflammation of the liver for >6 months.
  • Worsening injury leads to extensive fibrosis that occurs between portal tracts (portal bridging), nodular changes, and finally, cirrhosis.

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