Diagnostic tests for Hepatitis C

Dr Th Dhabali Singh *

Viral Hepatitis-C task force formed on August 28 2016 :: Pix - TSE

World Hepatitis Day falls on 28th July every year, the aim being bringing the world together under one single theme in order to raise awareness of viral hepatitis and the impact it has worldwide. The theme for World Hepatitis Day 2018 is “Eliminate Hepatitis”.

There are 325 million people that are living with viral hepatitis in the world, yet up to 290 million of these are unaware that they have it. In recognition of this, The World Hepatitis Alliance are launching a campaign in association with World Hepatitis Day, which aims to focus on “finding the missing millions”. World Health Organisation’s Global Strategy of Viral Hepatitis aims for complete elimination of viral hepatitis by 2030.

What is Hepatitis C?

Hepatitis C (HCV) is a virus that causes an infection of the liver that is characterised by liver inflammation and damage. Hepatitis C tests are a group of tests that are performed to detect, diagnose, and monitor the treatment of a hepatitis C viral infection. The most common test for HCV looks for antibodies in the blood that are produced in response to an HCV infection.

Other tests detect the presence of viral RNA, the amount of viral RNA present, or determine the specific subtype of the virus. HCV is spread by exposure to contaminated blood, primarily through the sharing of needles by intravenous drug users, but also by sharing personal items contaminated by blood such as razors, through unprotected sex with an infected person, via healthcare occupational exposure, and less commonly, from mother to baby during childbirth.

While HCV is not as contagious as hepatitis B, there is currently no vaccine to prevent infection. HCV infection is a common cause of chronic liver disease throughout the world. Many of those infected with HCV have no symptoms and are not aware of the condition. The acute HCV infection may cause few to mild and non-specific symptoms, and the chronic infection may remainquietly for many years before causing sufficient liver damage to affect liver condition. Hepatitis C infections cause increased risk of developing some other serious conditions.

o About 75-85% will develop chronic HCV infection.
o About 5-20% will develop cirrhosis over 20 years; recent projections suggest that almost 45% will eventually develop cirrhosis.
o HCV causes death in about 1-5% of those chronically infected who develop cirrhosis or liver cancer.

HCV diagnostic tests

Hepatitis C tests are used to screen for and diagnose a hepatitis C virus infection, to guide therapy and/or to monitor the treatment of an HCV infection.

An HCV antibody test is used to screen for past exposure and current infection. It detects the presence of antibodies to the virus, indicating exposure to HCV. This test cannot distinguish whether someone has an active or a previous HCV infection. There is some evidence that if the test is “weakly positive”, it may be a false positive case. It is recommended that all positive antibody tests be followed by an HCV RNA test that detects viral RNA in the blood to determine whether or not the person has an active infection.

The HCV antibody tests may be performed as part of an acute viral hepatitis panel to determine which of the most common hepatitis viruses is causing a person’s symptoms.

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

o HCV RNA Test, Quantitative (HCV Viral Load). It detects and measures the number of viral RNA particles in the blood. This test may be used to confirm the presence of the virus and diagnose an active infection. Viral load tests are also used before and during treatment.

o HCV RNA, Qualitative. This test is used to distinguish between a current or past infection. It is reported as “positive” or “detected” if any HCV RNA is found; otherwise, the report will be “negative” or “not detected”. This test is not frequently used any more.

o HCV Genotyping. This is used to determine the kind, or genotype, of the HCV present to help guide treatment. The drugs selected for treatment depend in part on the genotype of HCV infecting a person.

When is it done?

The HCV antibody testing may be done when someone has abnormal results on a liver panel or when the person shows signs or symptoms associated with hepatitis.

Most people with a recent infection with HCV have no symptoms or have mild ones that do not prompt the person to undergo HCV testing.

An HCV RNA test or viral load is ordered as a follow-up testing when an antibody test is positive to confirm an active infection. It is also done at the start of the treatment, periodically to monitor response to treatment, and after the completion of treatment to evaluate its effectiveness. A high or increasing viral load may be a sign that treatment is not successful.

On the other hand, a low or decreasing viral load may indicate that the treatment is working.

HCV genotyping is done when a person has been diagnosed with an HCV infection. It is often ordered before treatment is started to guide treatment selection.

Fibroscan in the Hepatitis C treatment and monitoring

The most important aspect in the evaluation of a patient with HCV infection is determining whether or not the person has cirrhosis. This is the most important part of staging because very specific guidelines define how one should proceed with patients with cirrhosis.

Fibroscan, also called transient elastographygives a measure of the stiffness of the liver. It is a non-invasive procedure to diagnose and monitor disease evolution in conjunction with treatment and collateral factors. Fibroscan gives instant results.

Are there other tests other than HCV RNA Test that are used to follow the disease?

Yes. Liver tests such as ALT and AST are used to assess liver injury. People who are infected with HCV but always have normal AST and ALT have very mild liver disease.

Other tests such as bilirubin can also be used; they are typically normal unless the person has developed cirrhosis. Sometimes a liver biopsy may be performed to determine the severity of liver disease.