Hepatitis C

• Has been exposed to someone with HCV
• Participates in high risk behaviors such as injecting street drugs
• Has abnormal liver function tests
• Has symptoms associated with liver disease, such as jaundice, dark urine, nausea, or unexpected weight gain or loss

The following tests may be used to screen for and/or detect HCV:

• Anti-HCV test detects the presence of antibodies to the virus, indicating exposure to HCV. This test cannot distinguish between someone with an active or a previous HCV infection. Usually, the test is reported as "positive" or "negative." There is some evidence that if the test is "weakly positive," it may be a false positive. The Centers for Disease Control and Prevention (CDC) suggests that weakly positive tests be confirmed with the HCV RIBA test before being reported.
• HCV recombinant immunoblot assay (RIBA) test is an additional test ordered to confirm the presence of HCV antibodies. In most cases, it can tell if the positive anti-HCV test was due to exposure to HCV (positive RIBA) or represents a false signal (negative RIBA). In a few cases, the results cannot answer this question (indeterminate RIBA). Like the anti-HCV test, the RIBA test cannot distinguish between a current or past infection.

The following tests may be used to diagnose a current infection and to guide and monitor treatment:

• HCV RNA test, Qualitative may be used to distinguish between a current or past infection. It is reported as a "positive" or "detected" if any HCV viral RNA is found; otherwise, the report will be "negative" or not detected." It may also be ordered after HCV treatment is complete to see if the virus has been eliminated from the blood. These tests are seldom used any more.
• HCV Viral Load (HCV RNA test, Quantitative) detects and measures the number of viral RNA particles in the blood. Viral load tests are often used before and during treatment to help determine response to treatment by comparing the amount of virus before and during treatment (usually at several time points in the first three months of treatment). Successful treatment causes a decrease of 99% or more (2 logs) in viral load soon after starting treatment (as early as 4-12 weeks) and usually leads to viral load being not detected even after treatment is completed. Some newer viral load tests can detect very low amounts of viral RNA.
• Viral genotyping is used to determine the kind, or genotype, of the HCV virus present. There are 6 major types of HCV; the most common (genotype 1) is less likely to respond to treatment than genotypes 2 or 3 and usually requires longer therapy (48 weeks versus 24 weeks for genotype 2 or 3). Genotyping is often ordered before treatment is started to give an idea of the likelihood of success and how long treatment may be needed.

• If you have ever injected illegal drugs
• If you received a blood transfusion or organ transplant before July 1992*
• If you have received clotting factor concentrates produced before 1987
• If you were ever on long-term dialysis
• For children born to HCV-positive women
• For health care, emergency medicine, and public safety workers after needlesticks, sharps, or mucosal exposure to HCV-positive blood
• For people with evidence of chronic liver disease

*The blood supply has been monitored in the U.S. since 1992, and any units of blood that test positive for HCV are rejected for use in another person. The current risk of HCV infection from transfused blood is about 1 case per two million transfused units.

Most people newly infected with HCV have no symptoms or ones that are so mild that they rarely prompt a person to visit a doctor and get tested for HCV. However, about 10-20% of people may experience symptoms such as fatigue, pain in the abdominal area, decreased appetite, and jaundice and may be tested for HCV.

A positive anti-HCV test may be confirmed with an HCV RIBA test, especially when the anti-HCV test is "weakly positive." Many physicians do not use RIBA since it still does not determine if a person is currently infected. Quantitative HCV-RNA is often ordered when the antibody test is positive to see if the infection is still present. HCV viral load and genotyping may be done when treatment is planned; viral load may be ordered periodically to monitor response to treatment and at the completion of treatment to evaluate its effectiveness.

Test results to detect, diagnose, and monitor HCV include:

An HCV viral load (HCV RNA quantitative) can indicate whether or not treatment is effective. A high or increasing viral load may be a sign that treatment is not successful whereas a low, decreasing, or undetectable viral load may imply that the treatment is working. According to the CDC, an undetectable viral load in a treated person's blood for 24 weeks after the end of the treatment means that the HCV infection has responded to therapy.

The results of the HCV genotype test identifies which type of HCV the person has and helps guide the type and often the length of treatment. There are at least six separate types (genotypes) of HCV numbered as 1 through 6 with at least an additional 50 subtypes that have been identified. Genotype 1 is the most common HCV genotype in the United States.

About 25% of those with HIV/AIDS also have an HCV co-infection, and their liver disease is likely to progress at an accelerated rate.