Transmission of hepatitis B virus in clinical laboratory areas

The transmission of hepatitis B virus (HBV) in clinical laboratory areas was delineated by the use of hepatitis B surface antigen (HBsAg) as presumptive evidence for the presence of the infective agent. Twenty-six (34%) of 76 environmental surfaces sampled were positive for HBsAg. The outer surfaces of blood- and serum-specimen containers had HBsAg contamination rates of 55% (six of 11) and 44% (four of nine), respectively. Subsequent handling of pipetting aids, marking devices, and other items led to their contamination and further dissemination of HBsAg. An assay instrument for complete determinations of blood cell counts was observed to splatter and drip blood during its operation. The contamination rate for environmental surfaces associated with this instrument was 15%. The data indicate that transmission of HBV in the clinical laboratory is subtle and mainly via hand contact with contaminated items during the various steps of blood processing. These data support the concept that the portal of entry of HBV is through inapparent breaks in skin and mucous membranes.