Topic Resources
Hepatitis A is caused by an
enterically transmitted RNA virus that, in older children and adults,
causes typical symptoms of viral hepatitis, including anorexia, malaise,
and jaundice. Young children may be asymptomatic. Fulminant hepatitis
and death are rare in developed countries. Chronic hepatitis does not
occur. Diagnosis is by antibody testing. Treatment is supportive.
Vaccination and previous infection are protective.
Hepatitis A virus (HAV) is a single-stranded RNA picornavirus. It
is the most common cause of acute viral hepatitis and is particularly
common among children and young adults.
In some countries, > 75% of adults
have been exposed to HAV. In the US in 2016, 2000 cases were reported,
and an estimated 4000 cases occurred (many cases are not recognized or
not reported)—a marked decrease from the 25,000 to 35,000 annual cases
before the hepatitis A vaccine became available in 1995 (1). Worldwide, an estimated 1.4 million cases of hepatitis A occur each year (2).
HAV spreads primarily by fecal-oral contact and thus may occur in
areas of poor hygiene. Waterborne and food-borne epidemics occur,
especially in developing countries. Eating contaminated raw shellfish is
sometimes responsible. Sporadic cases are also common, usually as a
result of person-to-person contact.
Fecal shedding of the virus occurs before symptoms develop and
usually ceases a few days after symptoms begin; thus, infectivity often
has already ceased when hepatitis becomes clinically evident.
General references
Symptoms and Signs
In children < 6 years old, 70% of hepatitis A infections are
asymptomatic, and in children with symptoms, jaundice is rare. In
contrast, most older children and adults have typical manifestations of viral hepatitis, including anorexia, malaise, fever, nausea, and vomiting; jaundice occurs in over 70%.
Manifestations typically resolve after about 2 months, but in some patients, symptoms continue or recur for up to 6 months.
Recovery from acute hepatitis A is usually complete. Fulminant hepatitis rarely occurs.
Diagnosis
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Serologic testing
In the initial diagnosis of acute hepatitis, viral hepatitis should be differentiated from other disorders causing jaundice (see figure Simplified diagnostic approach to possible acute viral hepatitis).
If acute viral hepatitis is suspected, the following tests are done to screen for hepatitis viruses A, B, and C:
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IgM antibody to HAV (IgM anti-HAV)
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Hepatitis B surface antigen (HBsAg)
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IgM antibody to hepatitis B core (IgM anti-HBc)
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Antibody to hepatitis C virus (anti-HCV) and hepatitis C RNA (HCV-RNA)
If the IgM anti-HAV test is positive, acute hepatitis A is
diagnosed. The IgG antibody to HAV (IgG anti-HAV) test is done (see
table Hepatitis A Serology)
to help distinguish acute from prior infection. A positive IgG anti-HAV
test suggests prior HAV infection or acquired immunity. There is no
further testing for hepatitis A.
HAV is present in serum only during acute infection and cannot be detected by clinically available tests.
IgM antibody typically develops early in the infection and
peaks about 1 to 2 weeks after the development of jaundice. It
diminishes within several weeks, followed by the development of
protective IgG antibody (IgG anti-HAV), which persists usually for life.
Thus, IgM antibody is a marker of acute infection, whereas IgG anti-HAV
indicates only previous exposure to HAV and immunity to recurrent
infection.
Table
Other tests
Liver tests are needed if not previously done; they include serum
alanine aminotransferase (ALT), aspartate aminotransferase (AST),
alkaline phosphatase, and bilirubin.
Other tests should be done to evaluate liver function; they
include serum albumin, platelet count, and prothrombin
time/international normalized ratio (PT/INR).
Treatment
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Supportive care
No treatments attenuate acute viral hepatitis, including
hepatitis A. Alcohol should be avoided because it can increase liver
damage. Restrictions on diet or activity, including commonly prescribed
bed rest, have no scientific basis.
For cholestatic hepatitis, cholestyramine 8 g orally once or twice a day can relieve itching.
Viral hepatitis should be reported to the local or state health department.
Prevention
Good personal hygiene helps prevent fecal-oral transmission of
hepatitis A. Barrier protection is recommended, but isolation of
patients does little to prevent spread of HAV.
Spills and contaminated surfaces in the home of patients can be cleaned with dilute household bleach.
Vaccination
The hepatitis A vaccine is recommended for all children beginning at age 1 year, with a 2nd dose 6 to 18 months after the first (see table Recommended Immunization Schedule for Ages 0–6 years).
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Diagnostic laboratory workers
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Men who have sex with men
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People who use injection or noninjection illicit drugs
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People with chronic liver disorders (including chronic hepatitis C) because they have an increased risk of developing fulminant hepatitis due to HAV
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People who receive clotting factor concentrates
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People who anticipate close contact with an international adoptee during the first 60 days after arrival from a country with high or intermediate HAV endemicity
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People who do not have stable housing or who are homeless
Preexposure HAV prophylaxis can be considered for day-care center employees and for military personnel.
Several vaccines against HAV are available, each with different
doses and schedules; they are safe, provide protection within about 4
weeks, and provide prolonged protection (probably for > 20 years).
Previously, travelers were advised to get the hepatitis A vaccine
≥ 2 weeks before travel; those leaving in < 2 weeks should also be
given standard immune globulin. Current evidence suggests immune globulin is necessary only for older travelers and travelers with chronic liver disease or another chronic disorder.
Postexposure prophylaxis
Postexposure prophylaxis should be given to family members and close contacts of patients with hepatitis A.
For healthy, unvaccinated patients aged 1 to 40 years, a single dose of hepatitis A vaccine is given.
For other patients, particularly those > 75 years old, those
with chronic liver disease, and immunocompromised patients, standard immune globulin
(formerly immune serum globulin) prevents or decreases the severity of
hepatitis A. A dose 0.02 mL/kg IM is generally recommended, but some
experts advise 0.06 mL/kg (3 to 5 mL for adults). It can be given up to 2
weeks after exposure, but the earlier, the better.
Key Points
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Hepatitis A virus is the most common cause of acute viral hepatitis; it is spread by the fecal-oral route.
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Children < 6 years old may be asymptomatic; older children and adults have anorexia, malaise, and jaundice.
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Fulminant hepatitis is rare, and chronic hepatitis, cirrhosis, and cancer do not occur.
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Treat supportively.
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Routine vaccination beginning at age 1 is recommended for all.
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Vaccinate people at risk (eg, travelers to endemic areas, laboratory workers), and provide postexposure prophylaxis with standard immune globulin or, for some, vaccination.
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