Assessment of hepatitis B "e" antigen and "e" antibody status--tests of status or status of tests?

Forty-seven sera that gave positive results in tests for hepatitis B surface antigen and core antibody were examined for the presence of "e" antigen and "e" antibody by various commercially available assays. Considerable discordance was observed between results of tests performed on the same sample in different assays. Examination of the sera for the presence of hepatitis B DNA failed to resolve the discrepancies. Increasingly, "e" antigen and its antibody are used as measures of infectivity in carriers of hepatitis B. The absence of reliable tests has implications for patients, for infection control within hospitals and for the implementation of Department of Health guidelines on safe working practices for hepatitis B-infected health care workers.