Hepatitis A

Hepatitis A is the most common cause of acute viral hepatitis in the world.

Epidemiology

  1. Incidence in the U.S. is thought to be underreported. Actual number of cases about 136,000 in 1991
  2. Predominantly fecal-oral transmission. Also contaminated food or water
  3. ~50% are of unknown origin.
  4. Because there is a viremic phase, transmission by blood contact is possible although rare.
  5. Incubation is 2-6 weeks with mean of 28 days. Patients are infectious 1-2 weeks prior to symptoms and may shed virus for one week post infection.
  6. ~33% of U.S. population has serological evidence of exposure, and this increases with age. 
  7. Risk factors
    1. Large families, especially lower socio-economic status

      2. daycare attendees
    2. working or living in facilities for the mentally handicapped.
Clinical Manifestations in Children
  1. Less than 10% of children < 6 years old will have clinical evidence of disease. The incidence increases with age and 40% of 6-14 year olds and 70% of those older than 14
  2. Signs and Symptoms
    1. nausea and vomiting
    2. diarrhea
    3. Jaundice
    4. loss of appetite
    5. Majority of cases are self limited and there is no chronic carrier state. Morbidity and mortality are rare. Unusual complications include fulminant hepatitis, cholestatic hepatitis, and recurrent hepatitis.
    6. Elevated serum aminotransferasess and bilirubin, and dark urine due to presence of bilirubin.
    7. Symptoms last 2-3 weeks in the majority of cases. 
Serologic Diagnosis
  1. Anti HAV IgM is found early in the course and may persist for 3-6 months. Will not be found in post-vaccinated states.
  2. IgG against HAV usually infers past infection and may last for years. 
Treatment
  1. Supportive
    1. IV fluids if dehydrated or vomiting
    2. Rest as needed
    3. Exclude from school or work for one week after onset of the illness.
Control Measures
  1. Immune globulin given intramuscularly is effective in 80-90% of cases when given within two weeks of contact.
  2. Recommendations for immunoglobulin
    1. Household contacts
    2. Sexual contacts
    3. Infants of mothers who develop Hepatitis A within two weeks prior to delivery and one week post delivery 
    4. Daycare centers
      1. if all attendees are over 2 and toilet trained, IG to all contacts in the room and employees in contact with the index case
      2. If HAV is diagnosed in an employee, or a child, or in the household contacts of two daycare attendees in a center where children are not toilet trained, IG is recommended for all children enrolled in the daycare.
    5. Not necessary for schoolroom exposure but if there has been transmission to others, IG indicated for contacts.
Hepatitis A Vaccine
  1. Inactivated vaccines marketed as Havrix and Vaqta
  2. May be given with other vaccines 
  3. Indications
    1. Travel to high endemic areas
    2. Native Americans or Native Alaskans in endemic areas
    3. Patients with chronic liver disease
    4. Homosexual or bisexual men
    5. IV drug users
    6. Hemophiliacs or or other users of blood products
    7. Occupational exposure
    8. Employees or resident in institutions with high incidence of Hepatitis A
  4. Post vaccination titers do not have to be monitored.
  5. Length of protection - because of limited time on the market, unknown. Preliminary data has protection lasting at least 4 years.
  6. May be given to immunodeficient patients
  7. In 2005, ACIP recommended universal hepatitis A vaccination for children between 12-23 months.  This is a two dose shedule with the second dose given 6-12 months later.  Both Havrix and Vaqta are recommended.   There is excellent protection after one dose of vaccine
References
  1. American Academy of Pediatrics Prevention of Hepatitis A Infections: Guidelines for Use of Hepatitis A Vaccine and Immune Globulin. Pediatrics December 1996.
  2. Tanuous H. Hepatitis A. Pediatrics in Review. 1999; 20:102.
  3. Pratt. D and Kaplan M. Evaluation of Abnormal Liver-Enzyme Results in Asymptomatic Patients NEJM Vol 342 no. 17 April 27, 2000
  4. Craig A.S. and Schaffner W.  Prevention of Hepatitis A with the Hepatitis A Vaccine. NEJM 2004 Vol 350 No5 pg 476
  5. Hochman j. Balisteri W. Chronic Viral Hepatitis. Pediatrics in Review. December 2003
  6. Leach C. Hepatitis A in the United States. Ped Inf Disease J. Vol 23(6) June 2004
  7. Victor J.C. Hepatitis A Vaccine versus Immune Globulin for Postexposure Prophylaxis. NEJM Oct 25, 2007
  8. Baker C.J. Another Success for Hepatitis A Vaccine. NEJM Oct 25, 2007
  9. Davis A, Rosenthal P. Hepatitis B in Children Pediatrics in Review April 2008
  10. MMWR. Recommendations for Identification and Public Health Mangement of Persons wih Chronic Hepatitis B Infections.  Sept 19, 2008