Trends and patterns in the transmission of bloodborne pathogens to health care workers

The key determinants of transmission of bloodborne pathogens are the dose and serum viral concentration of an exposure. This conclusion is supported by data showing that the rate of transmission of hepatitis B virus is elevated if the source patient's viral serum concentration is high and by a comparison of serum concentrations and rates of transmission for hepatitis B virus, HIV, and hepatitis C virus: As the mean serum viral concentration of each of these pathogens increases, the rate of transmission also increases. While there is evidence that the incidence of clinical hepatitis B has declined as a result of vaccine-induced immunity, the prevalence of hospital patients who are HBsAg-positive has actually increased. As the AIDS epidemic evolves and increasing numbers of patients with AIDS are hospitalized, the risk of exposure to HIV and hepatitis B virus can be expected to increase further. Thus, health care workers, many of whom work in an urban setting and are exposed to the blood and body fluids of patients, should be required to receive hepatitis B vaccine. Whereas hepatitis B virus transmission can be prevented by immunization of health care workers, controlling hepatitis C virus and HIV will require efforts to reduce the incidence and dosage of exposures to blood and body fluids. These strategies include the design and use of safe medical devices, targeted interventions based on occupation-specific hazards, the use of gloves and other barriers, and ongoing surveillance and analysis of exposures in the health care setting.