[Risk of hepatitis C virus infection by needlestick among medical employees]

Verletzungen mit Hepatitis-C-Virus-kontaminierten Nadeln

The risk of infection after injury with a needle contaminated with hepatitis C virus (HCV) is thought to be about 3%, but this assumption is mainly based on studies published in the 1990's, which were limited by small sample sizes and insensitive HCV-RNA assays. We therefore investigated needle injuries at the Hannover Medical School over a period of 6 years and performed a systematic review of the literature identifying 22 studies with a total of 6,956 injuries with HCV contaminated needles. Between 2000 and 2005, 1,431 occupational injuries were reported at our institution and two-thirds were needle injuries. Index patients were known to be HCV infected in 166 cases but there were no cases of HCV seroconversion during follow-up. Analysis of published data showed seroconversion rates of 0-10.3% with a mean of 0.75% (52/6,956). The risk of acute HCV infection was lower in Europe with 0.42% compared to Eastern Asia with 1.5% of cases where an HCV viremia was reported during follow-up. In summary, the risk of acquiring an HCV infection after a needlestick injury is lower than frequently reported. Worldwide differences in HCV seroconversion rates suggest that genetic factors might provide some level of natural resistance against HCV. Future studies should address not only the frequency of acute hepatitis but also factors associated with a higher risk of becoming HCV infected.

Accidental exposure to HCV antibody-positive blood in hospital and pre-emptive one-shot interferon alpha-2b treatment

AIMS

Infection with hepatitis viruses following blood exposure accidents, such as needle stick injuries, is a serious issue for medical staff. In particular, although accidental exposure to hepatitis C virus (HCV) occurs frequently, postexposure prophylactic measures have not been established yet. In this study we investigate the efficacy of recombinant alpha-2b interferon (IFN) as a single, 10 MU intramuscular injection for preventing transmission.

METHODS

264 incidents of accidental blood to HCV antibody-positive blood, occurring between 1993 and 2003 in the Social Insurance Chukyo Hospital, were surveyed. Accident reports, which described in detail the circumstances and the presence or absence of infectious disease in the blood, and accidental exposure to HCV antibody-positive blood was investigated.

RESULTS

Pre-emptive IFN treatment was given in 115 out of 157 cases occurring between 1993 and 1998. One case developed acute HCV. Phylogenetic analysis provided evidence that the accident caused the infection and the patient was cured by immediate IFN therapy. Between 1999 and 2003, the exposed were in principle followed-up without IFN treatment; IFN treatment was only given when requested. As a result, IFN was given in 14 of 107 cases. During this period, no transmission was observed.

CONCLUSION

Taken together, the benefits of pre-emptive IFN treatment were considered unremarkable and a follow-up without treatment, or immediate IFN therapy after confirmation of the onset, was recommended.

Accidental transmission of HCV and treatment with interferon

Accidental transmission of contagious pathogens, especially hepatitis C virus (HCV), by needlestick or other means as an occupational hazard for medical staff is of concern. We retrospectively analysed cases of work-related accidental injury with pathogens such as hepatitis B virus (HBV), HCV, syphilis and human immunodeficiency virus (HIV) reported to the centres for disease control at 15 hospitals (total 5776 beds) in the Gunma prefecture, Japan, from December 1990 to August 1993 (24.7 months). There were 416 such cases (16.8 cases/month), with an incidence of 0.2-3.5 accidents per month per hospital. Such accidents occurred in 297 (71.2%) nurses, 98 (23.5%) medical doctors, 13 (3%) laboratory technicians, four (1.0%) hospital maintenance workers, one (0.2%) assistant nurse, one secretary and two others. There were 323 (77.6%) injuries caused by needlestick, 42 (10.1%) from suture needles or surgical knife cuts, 17 (4.1%) from blood splatters from patients into the eyes or mouth, 10 (2.4%) from contact with injured skin and 24 (5.8%) simple skin contacts. Of the pathogens, 60.3% were HCV, 22.6% HBV, 5.8% syphilis, 0.7% HIV and 10.6% were of unknown origin. Four cases (1.6%) of HCV infection were found and treated with one or two courses of interferon therapy, and HCV was subsequently cleared. All four patients were cured with interferon therapy. None of the HBV-injured cases resulted in infection, possibly because of prophylaxis with HB immunoglobulin and HB vaccine. No HIV or syphilis infection was contracted. In summary, chronic HCV infection acquired as an occupational hazard can be cured by appropriate treatment, such as with interferon, after early detection of the infection.