The HBeAg test is used to detect the presence of the active hepatitis B virus. It is conducted to diagnose Hepatitis B virus infection in the initial stages of infection in a patient. The detection of HBe antigen in serum and plasma is an indicator of active infection and replicating virus. The disappearance of HBeAg and the appearance of anti-HBe together with other HBV markers allow the clinician to determine a prognosis, and to follow the progression of the disease from acute to chronic or recovered status.