BOX 2-3

CDC Acute Hepatitis C Case Definition

Clinical case definition:

An acute illness with a discrete onset of any sign or symptom consistent with acute viral hepatitis (e.g., anorexia, abdominal discomfort, nausea, vomiting), and either jaundice or serum alanine aminotransferase (ALT) levels >400 IU/L.

Laboratory criteria for diagnosis:

One or more of the following three criteria:

  1. Antibodies to hepatitis C virus (anti-HCV) screening test positive with a signal to cut-off ratio predictive of a true positive as determined for the particular assay as defined by CDC, OR

  2. Hepatitis C Virus Recombinant Immunoblot Assay (HCV RIBA) positive, OR

  3. Nucleic Acid Test (NAT) for HCV RNA positive

and, meets the following two criteria:

  1. IgM antibody to hepatitis A virus (IgM anti-HAV) negative, AND

  2. IgM antibody to hepatitis B core antigen (IgM anti-HBc) negative

Case classification:

Confirmed: A case that meets the clinical case definition, is laboratory confirmed, and is not known to have chronic hepatitis C.

Abbreviations: CDC, Centers for Disease Control and Prevention; HAV, hepatitis A virus; HCV, hepatitis C virus; RIBA, recombinant immunoblot assay; RNA, ribonucleic acid.

NOTE: URL for the signal-to-cutoff ratios:

SOURCE: CDC, 2009a.

example, for ALT, aspartate transaminase, immunoglobulin M (IgM) antibody to the hepatitis A virus, and IgM antibody to the hepatitis B core antigen (HBcAg)—are difficult for health departments to obtain, particularly because negative test results often are not automatically reported to health departments (Fleming et al., 2006). Because auxiliary test results are not systematically reported to health departments, surveillance staff must actively follow up with health-care providers to obtain them and other clinical indicators of acute disease. If the data cannot be obtained, either because the proper tests were not ordered or because there is insufficient staff to conduct followup, cases will be classified ambiguously as nonacute infections.

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