Treatment options for hepatitis C
A vast majority develop chronic illness
How big is the problem?
Worldwide, there may be more than
170 million cases. In this country estimates of prevalence range from 200,000 to 400,000.
There is significant variation in prevalence rates here among certain subgroups: 0.04 per cent of blood donors are positive for the virus rising to 1 per cent in genitourinary clinic attenders and up to 50 per cent in intravenous drug users.
There are six known major genotypes of the virus, which is transmitted parenterally. At least four out of 10 infected people have genotype 1. The most common strains seen in western Europe are 1, 2 and 3. In a large proportion there is no obvious cause and sexual transmission of hepatitis C is less common than for hepatitis B.
Concomitant infection of hepatitis B and C is more serious than infection with hepatitis C alone. Concomitant infection with HIV is thought to increase the risk of transmission. With a mother who is an HCV carrier
there is also a transmission rate of 6 per
cent from mother to child a significant statistic.
What are the typical symptoms following HCV exposure?
Many patients are completely asymptomatic following exposure. Although around 20 per cent develop an acute hepatitis picture, typically involving malaise, weakness, anorexia and jaundice. Other more non-specific symptoms include muscle pains, abdominal discomfort and right upper quadrant pain.
More worryingly, some 85 per cent of people exposed to the virus fail to clear their viral load and go on to develop a chronic hepatitis picture.
The rate of progress is highly variable, but about one of four of those infected will develop advanced liver disease or cirrhosis within two decades and a small percentage of these will progress to hepatocellular carcinoma. Around a third of exposed patients may never progress to a cirrhotic state, or if they do this can take up to 50 years to achieve.
What affects ability to clear a viral load?
This appears to be partly related to the genotype of the hepatitis C virus, which in turn determines the effectiveness of the body's immune response.
How effective are blood tests at interpreting HCV infection?
The standard is an ELISA-3 blood test, with a positive result suggesting the patient has been exposed to several HCV antigens. Unfortunately, false positives can be a problem so a recombinant immunoblot assay (RIBA test) is used which, should it be negative, makes hepatitis C exposure unlikely.
But it must be remembered that anti-HCV levels take some weeks to rise to discernible levels in the body and so a negative test may need to be repeated if alanine aminotransferase (ALT) liver function test remains abnormal.
The gold standard is the polymerase chain reaction test (PCR) which detects the viral RNA genome, but this has cost implications as it is expensive and time-consuming. It goes without saying a liver biopsy is mandatory to determine the extent of any liver damage before any treatment is considered.