Each of the six most common tests has a slightly different purpose: 

• Anti-HCV tests detect the presence of antibodies to the virus, indicating exposure to HCV. These tests cannot tell if you have an active viral infection, only that you were exposed to the virus in the past. Usually, the test is reported as "positive" or "negative". There is some evidence that, if your test is "weakly positive", it may not mean that you have been exposed to the HCV virus. In Australia a positive Anti-HCV test has to be confirmed by a different antibody test. If one test is "positive" or "weakly positive" and the second test is negative, this is termed a "discordant result". A discordant result often means that you have not been exposed to the HCV virus however sometimes this can mean you may have been exposed recently so it is likely that a repeat test will be requested.
• HCV RIBA test is an additional test to detect the presence of antibodies to the virus. It can determine if the positive anti-HCV test was due to exposure to HCV or represents a false signal. "Weakly positive" anti-HCV tests can be re-tested with HCV RIBA to see if they are positive or not. Like the anti-HCV test, the RIBA test cannot tell if you are currently infected, only that you have been exposed to the virus.
• HCV-RNA test identifies whether the virus is in your blood, indicating that you have an active infection with HCV. It is usually performed by a test called a qualitative HCV; the result is reported as a "positive" or virus "detected" if any virus is found; otherwise, the report will be "negative" or "not detected" if no virus is found. The test is also used after treatment to see if the virus has been eliminated from the body. This method is used for early detection and is one of the most sensitive methods for testing.
• Viral Load or Quantitative HCV tests measure the number of viral particles in your blood. Viral load tests are often used before treatment to help determine how long treatment needs to be given (along with other factors, such as your age, gender, the changes seen in a liver biopsy, and genotype, discussed below). With newer forms of treatment, it is also used to follow response to treatment by comparing the amount of virus before and after treatment.
• HCV Antigen testing is a test much like the RNA test in that it looks for the presence of the virus in the blood although rather than looking for the genetic material of the virus like the RNA test, this test looks for part of the virus called an antigen. While it can be used to help determine if someone is currently infected with Hepatitis C it is not commonly used.
• Viral genotyping is used to determine the kind, or genotype, of the virus present; there are currently 6 major types of HCV; the most common (genotype 1) in Australia is less likely to respond to treatment than genotypes 2 or 3 and usually requires longer therapy. Genotyping is often required before treatment is started to give an idea of the likelihood of success and how long treatment may be needed.

Hepatitis C infection is a common cause of chronic liver disease . About 75-85 per cent of those infected develop chronic hepatitis, and about 20 per cent of those develop cirrhosis. HCV testing is recommended in the following cases:

• If you have ever injected illegal drugs
• If you received a blood transfusion or organ transplantation before mid-1990*
• 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 Australia since February 1990, and any units of blood that test positive for HCV are rejected for use. The current risk of HCV infection from transfused blood in Australia is less than 1 case per million transfused units.

HCV testing is done in a sequential way. First an anti-HCV test is done. A positive anti-HCV test may be confirmed with an HCV RIBA test, especially if the test is "weakly positive" or "discordant". A positive anti-HCV test is usually followed by a Qualitative HCV-RNA test to see if the infection is still present. HCV viral load and genotyping may be done to plan treatment. Viral load and qualitative HCV RNA are also used to monitor response to treatment to see if the virus has been or is being eliminated.

If the antibody test result is positive by two different methods, it is likely you have been infected with hepatitis C, even if you have no symptoms.

A positive RIBA confirms that you had been exposed to the virus, while a negative RIBA indicates that your first test was probably a false positive and you have never been infected by HCV although to confirm typically further testing later on is required. The RIBA test may also be reported as "indeterminate", which means that the test cannot confirm whether you have been exposed to HCV or not.

A positive (or detectable) HCV RNA means that you are currently infected by HCV.

HCV antibodies usually do not appear until several months into an infection but will always be present in the later stages of the disease.

Ten percent of people with HCV have no recognised source for their infection.

Hepatitis C often leads to chronic hepatitis, which can progress to cirrhosis and liver cancer (hepatocellular carcinoma). Early detection of the virus can alert your doctor to monitor your liver function more closely than usual and to consider treating you if you are chronically infected. Being tested also reduces the risk of the virus being transmitted to another person. The majority of individuals infected present with no symptoms there HCV infection is more likely to be detected in the chronic phase. Some individuals will clear the virus spontaneously but most infections become chronic (they continue throughout the person's life unless successfully treated).

Yes. Liver tests, such as ALT and AST, are used to indicate ongoing liver injury. Persons who are still infected with HCV but always have normal AST and ALT probably have very mild liver disease and may not need treatment. Other liver tests, such as albumin, prothrombin time, and bilirubin can also be used; they are typically normal unless the person has developed cirrhosis. Sometimes a liver biopsy may be performed to determine how severe the liver damage is.

No. Currently, there is no vaccine available. Developing one has been difficult because the virus has several different molecular configurations, which are constantly changing.

Yes, there are currently quite a few drugs that can be used to treat HCV infection. Until relatively recently, a combination of two drugs (interferon and ribavirin) was used. New drugs to treat HCV are now available and work more effectively. The treatment chosen depends on many factors including your age, gender, the genotype and viral load of HCV you have and how much damage has occurred to your liver. It is possible to be cured from a HCV infection.

No. The test is only performed by qualified laboratory staff.

If a person has detectable HCV RNA in their blood, they have the potential to spread the disease to other people. The likelihood of giving your sex partner HCV is low, even if you have the virus in your blood; most doctors would recommend safe sex (such as using condoms), especially if you have more than one sex partner or are HIV positive. Pregnant women who have the HCV virus in their blood have about a 5% chance of spreading the infection to their infant. HCV is highly infectious if needles or (perhaps) razors are shared by an infected and an uninfected person. HCV cannot be spread by casual contact, even if you live in the same house with an infected person.