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The objectives of conducting surveillance for hepatitis C are to
- identify new cases and determine disease
incidence and trends;
- determine risk factors for infection and
disease transmission patterns;
- estimate disease burden; and
- identify infected persons who can be counseled
and referred for medical follow-up.
Various surveillance approaches are required to
achieve these objectives because of limitations of
diagnostic tests for HCV infection, the number of
asymptomatic patients with acute and chronic
disease, and the long latent period between infection
and chronic disease outcome.
Surveillance
for Acute Hepatitis C
Surveillance for acute hepatitis C -- new, symptomatic
infections -- provides the information necessary for
determining incidence trends, changing patterns of
transmission and persons at highest risk for infection. In addition, surveillance for new cases provides the
best means to evaluate effectiveness of prevention
efforts and to identify missed opportunities for
prevention. Acute hepatitis C is one of the diseases
mandated by the Council of State and Territorial
Epidemiologists (CSTE) for reporting to CDC's
National Notifiable Diseases Surveillance System. However, hepatitis C reporting has been unreliable
to date because most health departments do not have
the resources required for case investigations to
determine if a laboratory report represents acute
infection, chronic infection, repeated testing of a
person previously reported, or a false-positive result. Historically, the most reliable national data regarding
acute disease incidence and transmission patterns have
come from sentinel surveillance (i.e., sentinel counties
study of acute viral hepatitis). As hepatitis C prevention
and control programs are implemented, federal, state,
and local agencies will need to determine the best
methods to effectively monitor new disease acquisition.
Laboratory Reports
of Anti-HCV-Positive Tests
Although limitations exist for the use of anti-HCV-
positive laboratory reports to identify new cases and
to monitor trends in disease incidence, they potentially
are an important source from which state and local
health departments can identify infected persons who
need counseling and medical follow-up. Development of
registries of persons with anti-HCV-positive laboratory results might facilitate efforts
to provide counseling and medical follow-up and these registries could be used to provide
local, state, and national estimates of the
proportion of persons with HCV infection who have
been identified. If such registries are developed, the
confidentiality of individual identifying information
should be ensured according to applicable laws and
regulations.
Serologic
Surveys
Serologic surveys at state and local levels can
characterize regional and local variations in
prevalence of HCV infection, identify populations
at high risk, monitor trends, and evaluate prevention
programs. Existing laboratory-based reporting of HCV-positive test results cannot provide
this
information because persons who are tested will
not be representative of the population as a whole,
and certain populations at high risk might be under represented. Thus, data from newly
designed or
existing serologic surveys will be needed to monitor
trends in HCV infection and evaluate prevention
programs at state and local levels.
Surveillance
for Chronic Liver Disease
Surveillance for HCV-related chronic liver disease can provide information to measure the
burden of disease, determine natural history and risk factors, and evaluate
the effect of therapeutic and prevention measures on
incidence and severity of disease. Until recently, no
such surveillance existed, but a newly established
sentinel surveillance pilot program for physician-diagnosed chronic liver disease will provide baseline
data and a template for a comprehensive sentinel
surveillance system for chronic liver disease. As the
primary source of data regarding the incidence and
natural history of chronic liver disease, this network
will be pivotal for monitoring the effects of education, counseling, other prevention
programs, and newly
developed therapies on the burden of the disease.
FUTURE DIRECTIONS
To prevent chronic HCV infection and its sequelae, prevention of new HCV infections should
be the
primary objective of public health activities. Achieving
this objective will require the integration of HCV
prevention and surveillance activities into current
public health infrastructure. In addition, several
questions concerning the epidemiology of HCV
infection remain, and the answers to those questions
could change or modify primary prevention activities.
These questions primarily concern the magnitude
of the risk attributable to sexual transmission of HCV
and to illegal noninjecting-drug use.
Identification of the large numbers of persons in the
United States with chronic HCV infection is
resource-intensive. The most efficient means to achieve
this identification is unknown, because the prevention
effectiveness of various implementation strategies has
not been evaluated. However, widespread programs to
identify, counsel, and treat HCV-infected persons,
combined with improvements in the efficacy of
treatment, are expected to lower the morbidity and
mortality from HCV-related chronic liver disease
substantially. Monitoring the progress of these
activities to determine their effectiveness in achieving
a reduction in HCV-related chronic disease is important.

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