Occupational Exposure to Hepatitis C Virus: A Dilemma

Hepatitis C virus (HCV) is transmitted most efficiently by large or repeated percutaneous exposures to blood, such as through the transfusion of blood or blood products from infectious donors or the sharing of contaminated needles among injection drug users. Other bloodborne viruses, such as the hepatitis B virus, are transmitted not only by overt percutaneous exposures, but by mucous membrane and inapparent parenteral exposures as well. Although these types of exposures are prevalent among healthcare workers, the risk factors for HCV transmission in this occupational setting are not well defined. A case-control study of patients with acute non-A, non-B hepatitis conducted prior to the discovery of HCV found a significant association between acquiring disease and healthcare employment, specifically patient care or laboratory work.1 Seroprevalence studies have reported antibody to HCV (anti-HCV) rates of 1% among hospital-based healthcare workers in Western countries and 4% among such workers in Japan.2 In the one study that assessed risk factors for infection, a history of accidental needlesticks was associated independently with anti-HCV positivity.3 Case reports have documented the transmission of HCV infection from anti-HCV-positive patients to healthcare workers as a result of accidental needlesticks or cuts with sharp instruments.2 In the study reported by Lanphear et al in this issue4 on the follow-up of healthcare workers who sustained a variety of different types of exposures to blood from anti-HCV-positive patients, 3 (6%) of 50 with needlestick exposures seroconverted to anti-HCV on the basis of second-generation enzyme immunoassays (EIA) and supplemental testing. A fourth healthcare worker who sustained a scalpel laceration from an anti-HCV-positive source contracted clinical non-A, non-B hepatitis without anti-HCV seroconversion. Among patients with HCV infection, the secondgeneration EIAs detect anti-HCV in approximately 90%2; thus, in about 10% of persons with HCV infection, the diagnosis can be made only with researchbased detection methods, such as polymerase chain reaction (PCR) testing for HCV RNA. If we assume that the fourth healthcare worker also contracted hepatitis C, then the risk of HCV infection after a total of 57 exposures to needlesticks or sharps was 7%; 2 of the 4 infected healthcare workers developed clinical hepatitis. These results are consistent with a similar study reported from Japan.5 In this study, five of 76 healthcare workers with needlestick exposures to anti-HCV-positive patients seroconverted to anti-HCV for an incidence of 7%; however, an additional two infections were detected by PCR for an overall incidence of 9%. When exposures only to HCV RNApositive source patients were included (68 of 76), the overall incidence of HCV infection was 10%. Liver enzyme elevations developed in 4 of the 7 infected healthcare workers. Although no infections were detected among the small number of healthcare workers who sustained mucous membrane or open skin lesion exposures in the study by Lanphear et al, a recent case report has documented the transmission of HCV from a blood splash to the conjunctiva.6