National case definition: Hepatitis C

Date of last revision:  August 2011

Date of last review: August 2018

National notification

Only confirmed cases of disease should be notified.

Type of surveillance

Routine case-by-case notification to the federal level

Case classification

Confirmed case – acute or recent infection 

Detection of hepatitis C virus antibodies (anti-HCV) or hepatitis C virus RNA (HCV RNA) in a person with discrete onset of any symptom or sign of acute viral hepatitis (see Clinical evidence) within 6 months preceding the first positive HCV test

and

negative anti-HAV IgM, and negative anti-HBc IgM or HBsAg tests

and

serum alanine aminotransferase (ALT) greater than 2.5 times the upper normal limit

or

Detection of hepatitis C virus antibodies (anti-HCV) in a person with a documented anti-HCV negative test within the preceding 12 months

or

Detection of hepatitis C virus RNA (HCV RNA) in a person with a documented HCV RNA negative test within the preceding 12 months

Confirmed case – unspecified (including chronic and resolved infections)

Detection of hepatitis C virus antibodies (anti-HCV)

or

Detection of hepatitis C virus RNA (HCV RNA)

Laboratory comments

If diagnosis is based on anti-HCV alone, it should be confirmed by HCV RNA, immunoblot, a second manufacturer’s EIA, or based on an EIA signal to cut-off ratio predictive of a positive immunoblot.

If diagnosis is based on HCV RNA alone, a repeat test is recommended.

Anti-HCV testing should not be performed in infants under 18  months of age since a positive anti-HCV result may represent maternal antibody. Since vertical transmission of HCV infection usually occurs around the time of birth, if testing for HCV RNA is considered, it should be delayed for 4 to 12 weeks post-partum to avoid false negative result. Cord blood may be contaminated by maternal blood and should not be used for anti-HCV or HCV RNA testing.

The HCV seroconversion window period is approximately 5-10 weeks; it is estimated that 30% of acute infections may be missed if anti-HCV is the only marker of infection used during this time period. HCV RNA is detectable within 2-3 weeks of infection and, in the context of clinical illness, can identify acute HCV infection even in the absence of anti-HCV. In immunocompromised individuals, seroconversion can be delayed for up to one year, and some may never develop anti-HCV. These individuals may need to undergo HCV RNA testing.

Individuals who have had a sustained virologic response (SVR) for six months post-treatment and become HCV RNA positive within 12 months of SVR should be considered as having a new recent infection for surveillance purposes, even though some of these cases may be post-treatment relapses.

Approximately 25% (range, 15% to 45%) of HCV infections will resolve spontaneously. These individuals will typically demonstrate anti-HCV without detectable HCV-RNA.

Clinical evidence

Onset may be discrete but is more often insidious. Disease flares in chronic HCV infection may present similar symptoms and signs. More than 90% of acute infections are asymptomatic.

Clinical symptoms and signs of acute viral hepatitis include anorexia, abdominal discomfort, nausea, vomiting, malaise, fatigue, dark urine, pale stools and jaundice.

ICD code(s)

ICD-10 code(s)

B17.1, B18.2

ICD-9 code(s)

070.70, 070.71, 070.41, 070.44, 070.51, 070.54

References

Case Definitions for Communicable Diseases Under National Surveillance - 2009. Canada Communicable Disease Report; November 2009, 35S2. Retrieved April 2011, from http://www.phac-aspc.gc.ca/publicat/ccdr-rmtc/09vol35/35s2/index-eng.php