Nosocomial transmission of bloodborne viruses from infected health care workers to patients.

Abstract

1Departments of Pathology and Laboratory Medicine, Medicine, and Microbiology and Infectious Diseases, University of Calgary, Calgary, Alberta; 2Queen Elizabeth II Health Sciences Centre and Dalhousie University, Halifax, Nova Scotia Correspondence: Dr John Conly, Departments of Pathology and Laboratory Medicine, Medicine, and Microbiology and Infectious Diseases, Room 930, 9th Floor, North Tower, 1403 29th Street Northwest, Calgary, Alberta T2N 2T9. Telephone 403-944-8222, fax 403-944-1095, e-mail jconly@ucalgary.ca and Dr Lynn Johnston, Department of Medicine, Room 5014 ACC, Queen Elizabeth II Health Sciences Centre, 1278 Tower Road, Halifax, Nova Scotia B3H 2Y9. Telephone 902-473-5553, fax 902-473-7394, e-mail ljohnsto@dal.ca T risks to health care workers (HCWs) of occupationallyacquired infection with hepatitis B virus (HBV), human immunodeficiency virus (HIV) and, to a lesser extent, hepatitis C virus (HCV) have been reasonably well quantified (1). Evidence from the HIV and HBV experience suggests that the risk of infection is increased where the level of viremia is high, as manifested by high HIV viral load or the presence of hepatitis B e antigen (HbeAg) (1). It has also been recognized that patients may acquire one of these viruses following significant exposure to the blood of an infected HCW (2-4). While the magnitude of this risk to patients is considerably less than that to HCWs, the 1990 report by the Centers for Disease Control and Prevention (CDC) that a Florida dentist had transmitted HIV to patients in the course of dental care triggered widespread public concern about the risk of infection from HCWs. In 1991 CDC published recommendations for preventing HIV and HBV transmission to patients, which included the recommendation that HCWs who are infected with HIV or HBV (and HbeAg positive, a marker of higher infectivity) should not perform exposure-prone procedures unless they have sought counsel from an expert review panel (5). In 1998, Health Canada published guidelines for the management of HCWs infected with HBV, HCV, and/or HIV (6). Both these documents generated controversy at the time of their publication. Since that time, however, several provincial regulatory bodies have formed committees to advise physicians infected with these bloodborne pathogens (BBPs) regarding their practice. This article reviews what we know about the transmission of HBV, HCV and HIV from infected HCWs to patients in medical and dental settings.