PCR and Hepatitis C transmission
Introduction
PCR tests (polymerase chain reaction tests) provide considerable benefit for some people with hepatitis C virus (HCV) in their capacity to determine a person’s level of potential risk to transmit HCV to others.Analysis of 30 international research studies suggests that HCV transmission does not occur in cases where the blood source is HCV PCR negative.
Such awareness will be of great benefit for people concerned about transmission risk associated with needlestick injury or pregnancy and childbirth.
Many pregnant women with a positive HCV antibody result don’t actually have hepatitis C (also called hep C) due to either a false positive antibody test at diagnosis (they never actually had hep C) or their clearance of HCV soon after infection (this occurs in 20-30 per cent of people).
Women who are PCR negative will have almost no risk of passing on the virus to their baby compared to women who are both HCV antibody and PCR positive — in whom the risk of passing on the virus to their baby is about 6 per cent.
What is PCR (RNA)?
RNA testing refers to an advanced technology that is used to detect, in this case, ribonucleic acid from HCV.Several types of RNA technologies exist with the most commonly used version being the polymerase chain reaction (PCR) test. Less commonly used versions include the transcription mediated amplification (TMA) test, which is used as a screening test by Australian blood banks, and the branched chain DNA (bDNA) test, which is generally used as a research tool.
Unlike the HCV antibody tests that look for signs that the body has previously mounted an immune response to HCV, the PCR test looks for actual presence of the virus.
There are 3 types of PCR tests:
- HCV PCR viral detection test — looks for the virus, sometimes called ‘qualitative test’;
- HCV PCR viral load test — looks for the virus and estimates how many HCV viruses per mL of blood, sometimes called ‘quantitative test’; and
- HCV PCR genotype test — looks for the virus, and determines the particular type/s of HCV.
Healthcare settings
In regards to needlestick and other sharps injury in healthcare settings, attaining voluntary PCR testing of source individuals is recommended as a NSW Health recommendation.In NSW, healthcare workers who perform exposure-prone procedures must be aware of their HCV status. Those who are HCV PCR positive must not perform exposure-prone procedures (see NSW Health circulars, PD2005_311 and PD2005_162).
Exposure-prone procedures are those with potential for a healthcare worker to bleed into a patient as the result of a sharps injury, e.g. surgical procedures in body cavities. The NSW Department of Health has a longer and more precise definition to guide healthcare workers (see above circulars).
HCV transmission risk
The key HCV transmission prevention message will always remain ‘be blood aware and avoid blood-to-blood contact’. To adopt any other behaviour would place other people at risk of contracting HCV, or acquiring an HCV re-infection (i.e. infection with a different type of HCV genotype).There is the additional risk of transmitting other bloodborne infections, e.g. HIV or hepatitis B.
In any situation involving potential blood-to-blood contact, it’s important for everyone to assume that they, and all others, are potentially infectious.
If someone with hep C finds out they are PCR negative, they’d be making a big mistake in sharing any drug injecting equipment, snorting straws, razor blades or razors, tattooing equipment, toothbrushes or other equipment that could transfer blood.
Last Reviewed: 01 May 2007
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