Author: Dr Tony Williams FFOM, Consultant Occupational Physician, Working Fit Ltd
Date: 21 November 2015
The Hepatitis C virus is a Flavivirus closely related to those causing dengue and yellow fever. It is a spherical, enveloped, single-stranded RNA virus. The RNA dependent RNA polymerase required for replication lacks proofreading capabilities, so replication leads to a large number of mutant viruses; this represents a challenge to immune-mediated control and difficulty with vaccine development.
Transmission is by blood transfer, most commonly by injecting drug misuse. It is around ten times harder to catch than Hepatitis B. There are around 250,000 cases in UK. While some patients develop a rapid immune response and clearance of the virus, around 75-85% develop chronic Hepatitis C infection and 20-30% go on to develop severe long-term morbidity. Hepatitis C is the primary cause of chronic liver disease in around 25% of patients, alcohol is responsible for a similar number, and a further 15% are due to the combined effects of Hepatitis C and alcohol.
Twenty percent of chronic carriers develop cirrhosis in 20 years, with half of these developing hepatocellular carcinoma. For those who have acquired Hepatitis C through transfusion, this risk doubles to 40% in 20 years. The rate and likelihood of disease progression is increased by alcohol, immunosuppression (including HIV infection) and obesity.
Those found to be infected show a good response to treatment, currently with pegylated interferon and ribavirin. Cure rates above 60% within a year can be expected. Cure is considered to result when no Hepatitis C RNA is detectable in standard laboratory tests over a period of at least six months.
Members of staff known to have been exposed to the blood of a Hepatitis C positive patient through sharps injury should continue to work normally, but should have Hepatitis C RNA polymerase chain reaction testing six weeks after exposure. Twelve weeks after exposure this should be repeated, along with Hepatitis C antibody testing. Six months after exposure further Hepatitis C antibody testing should be undertaken. Repeat negative testing indicates no infection. Those testing positive should cease undertaking EPPs immediately and should be referred as soon as possible for specialist assessment by a gastroenterologist (DH, 2002).
Hepatitis C infected health care workers who have been treated with antiviral therapy may return to EPPs if they have tested negative to Hepatitis C RNA for at least six months after cessation of treatment. They should have one further check for Hepatitis C RNA another six months later. No further testing is required under DH policy (DH, 2002). Testing may, however, be appropriate (see below).
Current standard laboratory tests cannot demonstrate complete clearance of virus, but report that the virus is undetectable. In these situations infectivity is likely to be so low that it is safe to return to EPPs and reactivation of infection is unlikely so no further testing is required. There is evidence that infection remains within hepatocytes, and can be reactivated following treatment with monoclonal antibodies (such as Rituximab) and other immunosuppressants (such as TNF-α inhibitors) including cancer chemotherapy (Sagnelli et al., 2012, Watanabe and Tanaka, 2013, Yazici et al., 2014).
There are only a few studies in this area, most are retrospective and there are conflicting results (Sansone et al., 2014). DH policy does not require further testing, however it would appear prudent to recommend further Hepatitis C RNA screening in previously cleared health care workers who have subsequently required treatment with immune suppressant therapy (Murdaca et al., 2015). Treating clinicians are likely to undertake this testing anyway during immunosuppressive treatment, and would be expected to inform their patient if a positive result for Hepatitis C is found. Health care workers are themselves responsible for informing their employer (through occupational health) if they are found to be Hepatitis C positive, however occupational health staff need to be aware of the risk, and take appropriate action.
DH 2002. Hepatitis C infected health care workers. In: HEALTH, D. O. (ed.). London.
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YAZICI, O., SENDUR, M. A. & AKSOY, S. 2014. Hepatitis C virus reactivation in cancer patients in the era of targeted therapies. World J Gastroenterol, 20, 6716-24.