Occupational exposure to hepatitis B virus in hospital personnel: infection or immunization?

In a seroepidemiologic survey of 624 health workers representing a spectrum of exposure to blood and patients, the authors detected serologic markers of hepatitis B virus infection in 16%, significantly greater than the 5% prevalence in 462 volunteer blood donors (p less than 0.001). Frequency of hepatitis B serologic markers increased as a function of contact with blood, previous hepatitis history, years in occupation, and age but not as a function on contact with patients, years of education, previous needlestick, transfusion or globulin injection. The inclusion of testing for antibody to hepatitis B core antigen (anti-HBc) enhanced the sensitivity of surveillance by identifying an additional 3% of hospital personnel with hepatitis B exposure and proved to be a better indicator of intense exposure to blood and hepatitis B than antibody to hepatitis B surface antigen (anti-HBs). In addition, anti-HBc testing discriminated between the 47 (62%) of the 76 anti-HBs-positive health workers, predominantly those most intensely exposed to blood, who had anti-HBc and the 29 (38%), predominantly those with low-intensity blood contact, who did not. The association of the anti-HBs-positive/anti-HBc-negative pattern with infrequent blood contact suggests that in the setting of continuous, low intensity exposure to hepatitis B, health workers may become naturally immunized with hepatitis B surface antigen rather than infected with hepatitis B.