New CDC
National Center for Health Statistics Report Looks at Trends in
Hepatitis A, B, and C
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| SUMMARY:
Overall viral hepatitis incidence rates have fallen
over the past several years for a variety of reasons,
ranging from vaccination for hepatitis A and B to a
reduction in transmission risk behaviors for hepatitis
C, according to a new report from the Centers for
Disease Control and Prevention (CDC) National Center
for Health Statistics (NCHS). Certain subgroups remain
at elevated risk, however, and while new hepatitis C
infections have decreased, the infected population is
growing older and reaching the age of developing advanced
liver disease. |
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By
Liz Highleyman
The
NCHS compiled the new report to learn more about changes in the
3 most common types of viral hepatitis in the U.S. Hepatitis A
is transmitted through contaminated food and water and resolves
on its own without treatment. Hepatitis B and C are blood-borne
(e.g., transmitted through sharing needles or personal care items)
and can also be transmitted via sex or from mother-to-child during
pregnancy or delivery; both can become chronic, life-long infections.
Hepatitis A and B can be prevented with effective vaccines, but
there is no vaccine for hepatitis C.
NCHS
investigators used data from the National Health and Nutrition
Examination Survey (NHANES), an ongoing cross-sectional survey
designed to monitor the health and nutritional status of the civilian,
non-institutionalized U.S. population. The survey consists of
interviews conducted in participant's homes, standardized physical
examinations, and laboratory blood tests. Importantly, NHANES
does not include military personnel, people living in institutions
such as group homes and long-term care facilities, prisoners,
or homeless people. Since it does not count some of the groups
at highest risk for viral hepatitis, it likely underestimates
true population-wide rates.
Key
Findings
Hepatitis A virus (HAV):
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HAV
antibody prevalence has increased among U.S. born individuals
aged 6-19 years -- from 8% in 1988-1994 to 35% in 2007-2008
-- probably due to increased vaccination of children. |
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HAV
antibody positive rates among older people, in contrast, have
declined, most likely reflecting a decrease in exposure. |
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Mexican-Americans
have a significantly higher HAV antibody positive prevalence
among both children and adults compared with non-Hispanic
whites and blacks. |
Hepatitis
B virus (HBV):
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The
overall prevalence of HBV infection has decreased markedly
in recent years among all except the 40-59 age group. |
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This
decrease is attributable to widespread vaccination, which
has been recommended for infants since 1991. |
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By
2003-2006, more than 90% of children had received at least
1 dose of the hepatitis B vaccine, and by 2008 the rate of
HBV infection among young people age 6-19 approached zero. |
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HBV
prevalence is highest among foreign-born (largely Asian) individuals,
at 10%, but the rate is also high among blacks (9%) compared
with whites (about 2%) and Mexican-Americans (about 3%). |
Hepatitis
C virus (HCV):
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Overall
HCV prevalence decreased between 1988-1994 and 2007-2008. |
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Prevalence
continues to decrease among people at highest risk, such as
injection drug users, likely due to effective prevention efforts. |
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The
peak age of HCV infection is shifting to older age groups,
which suggests a majority of infected individuals were infected
many years ago. |
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In
1988-1994, the 30-39 age group had the highest HCV prevalence
rate (about 4%), but this shifted to the 40-49 age group from
1999 on. |
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HCV
remains the most common chronic blood-borne infection in the
U.S., largely because 70%-85% of those with acute infection
go on to develop chronic disease (versus about 5% of adults
infected with HBV). |
HCV
infection prevalence, by age and time periods: NHANES
r
estimate may be unstable because the relative standard error is
greater than 30%.
p estimate may be unstable because it is based on less than 10
positive persons.
NOTE: HCV is hepatitis C virus.
Taken
together, these findings illustrate the benefits of effective
prevention -- both vaccination and behavior change -- and underscore
the need to increase prevention efforts targeting groups that
continue to have higher infection rates relative to the rest of
the population.
The full NCHS viral hepatitis reports is
available online.
3/16/10
Reference
GM
McQuillan, D Kruszon-Moran, MM Denniston, and Hirsch R. Viral
Hepatitis. NCHS Data Brief No. 27. March 2010
