Alphabet soup: Differentiating viruses that cause hepatitis
H. CodyMeissner, M.D., FAAP
Five distinct hepatotropic viruses cause viral hepatitis: hepatitis A (HAV), hepatitis
B (HBV), hepatitis C (HCV), hepatitis D (HDV) and hepatitis E (HEV). These unrelated
viruses cause a similar syndrome typically consisting of nausea, malaise, abdominal
pain and jaundice. The course of acute hepatitis is clinically indistinguishable among
the different viruses.
Infection caused by HBV or HCV may result in chronic infection. This means many chronically
infected people are unaware they are infected until late-stage liver disease develops.
Which of the following statements are true?
a) About three-quarters of the estimated 1 million people in the United States who
are chronically infected with HBV were born outside the United States.
b) In recent years, multistate outbreaks of HAV have been linked to imported pomegranate
arils (seeds) from Turkey, frozen strawberries from Egypt and scallops from the Philippines.
c) All infants with a birth weight of 2,000 grams or more should receive hepatitis
B vaccine within 24 hours of birth.
d) Most hepatitis virus infections are symptomatic.
e) Most reported cases of acute HCV occur among young people who live primarily within
the Appalachian, Midwestern and New England regions of the country.
Answer: a, b, c and e are true
Laboratory diagnosis of hepatitis A is based on the detection of serum IgA antibody
against the virus. In 2016, 32 states had hepatitis A rates that exceeded the Healthy
People 2020 goal of 0.3 or fewer cases/100,000 population. Approximately 50% of reported
cases occurred among people with no known risk exposures/behaviors for hepatitis A
during the two months prior to illness onset.
Hepatitis A vaccines were licensed in 1995 and 1996. These vaccines provide long-term
protection against infection. Because of similarities in the epidemiology of hepatitis
A viruses and polioviruses, it is anticipated that adherence to the hepatitis A vaccination
schedule recommended by the Academy and the Centers for Disease Control and Prevention
(CDC) will stop viral transmission and result in the elimination of HAV as has occurred
With the widespread adoption of the hepatitis B vaccine, rates of reported hepatitis
B infection declined sharply after the 1990s. Since 2012, approximately 3,000 cases
have been reported annually. After adjusting for underreporting, the number of new
cases in the United States in 2016 was estimated to be 20,000.
The risk of chronic hepatitis B is inversely related to age of infection and ranges
from 90% for infants who acquire infection at birth to 5% among adults who experience
a primary infection. People with chronic infection often are unaware they are infected
and can infect others. About three-quarters of chronic HBV infections occur among
people born outside the U.S., and a disproportionate number occur among Asian/Pacific
Effective HBV vaccines have been available in the U.S. since 1981. Recommendations
for the use of these vaccines have been revised several times to maximize elimination
of HBV transmission. Current recommendations include:
universal vaccination within 24 hours of birth for medically stable infants weighing
at least 2,000 grams,
screening of all pregnant women and ensuring prophylaxis for infants born to hepatitis
B surface antigen-positive mothers,
routine vaccination of unvaccinated children and adolescents,
vaccination of adults at increased risk of infection, and
vaccination of people with other causes of chronic liver disease.
HCV infection rates increased more than three-fold from 2010 through 2016. Most acute
infections occur in urban areas among young adults who inject drugs, particularly
in states within the Appalachian, Midwestern and New England regions of the country.
Of all people living with HCV infection, about 75% were born from 1945 through 1965.
The great majority of acute HCV infections are not reported because few people experience
symptoms. An estimated 41,000 new HCV infections occurred in 2016, after adjusting
for underreporting. Estimates suggest approximately 3.5 million people or 1% of the
population are infected with HCV.
Hepatitis D infection is caused by a defective RNA virus that requires coinfection
with HBV for replication. HDV virus infection occurs only in people with acute or
chronic HBV infection. HDV infection is prevented by HBV vaccination.
Hepatitis E virus first was recognized as a unique cause of hepatitis in 1980 during
waterborne epidemics of disease in India related to inadequate sanitation. HEV causes
both sporadic cases and outbreaks, especially in Asia, Africa, the Middle East and
Central America. Outbreaks are particularly problematic in refugee camps. Pregnant
women are at significant risk with a case-fatality rate as high as 30%.
In the industrialized countries of Europe, HEV seroprevalence rates range from 12%
in the United Kingdom to 50% in areas of France. A 2011 CDC report described an infection
rate in the United States of seven infections/1,000 people/year. Most symptomatic
cases of HEV infection in the U.S. are related to travel to an endemic country. No
hepatitis E vaccine has been licensed by the Food and Drug Administration for use
in the U.S.
Dr. Meissner is professor of pediatrics at Floating Hospital for Children, Tufts Medical
Center. He also is an ex officio member of the AAP Committee on Infectious Diseases
and associate editor of the AAP Visual Red Book.