Certification Board of Infection Control and Epidemiology (CBIC) Practice Exam 2025 – The All-in-One Guide for Exam Success

The presence of the Hepatitis B surface antigen (HBsAg) is a key serological marker indicating that an individual is currently infected with the Hepatitis B virus (HBV) and is potentially infectious. When HBsAg is detected in a person's blood, it signifies active viral replication and thus the likelihood of transmission to others.

In the context of Hepatitis B infections, HBsAg positivity suggests that the virus is present in the body and the individual can spread the virus through blood and body fluids. This is crucial for infection control practices, as those who are HBsAg positive need to be managed appropriately to reduce the risk of further transmission.

In contrast, the presence of HBsAb indicates past infection and immunity, while HBeAg is associated with higher levels of viral replication but does not independently designate infectiousness like HBsAg does. The absence of HBsAg means that the person is not currently infected. Consequently, the detection of HBsAg is the definitive marker for identifying potentially infectious carriers of Hepatitis B.