Detection Methods for Study of the Stability of Hepatitis B Antigen on Surfaces

As a prelude to epidemiologic studies on the transmission of hepatitis B by personnel in hemodialysis units, a series of experiments was designed to determine the inactivation characteristics of hepatitis B antigen (HB Ag) on stainless steel and cotton surfaces and the efficiency of the swab-rinse and other methods for recovering HB Ag from dried blood on surfaces. Exposure of HB Ag-positive blood to constant conditions (25 C and 42% relative humidity) for 14 days resulted in a loss of only 15%-20% of antigenic activity. Virtually no reduction in HB Ag occurred on cotton swabs after a seven-day shipping cycle. Recovery of HB Ag from dried blood on stainless steel surfaces by the swab-rinse technique was essentially 100% efficient. In general, the results of this study indicate that, with appropriate sampling and processing techniques, HB Ag can be detected in an environment contaminated with blood or fluid that contains significant levels of antigen.