To determine the endemicity of hepatitis B, what should be measured ?

Ans. is 'a' i.e., HBsAg HBsAg testing is widely used as a marker of HBV infection in epidemiological surveys. Serological markers for HBV Serological markers for HBV infection are :? HBs Ag (surface antigen or Australia antigen) : It is the first marker which appears in the serum. It is the epidemiological marker for HBV infection. HBc Ag (core antigen) : It is not demonstrable in serum because it is enclosed by HBsAg coat. HBe Ag (envelope antigen) : It is marker of active replication and high infectivity. It is qualitative marker of replication. HBs Ag carrier mothers who are HBe Ag positive almost invariably (> 90%) transmit hepatitis B infection to their offspring, where as HBs Ag carrier mothers with anti HBe rarely (10 to 15%) infect their offspring. Anti-HBc Ag : It is the first antibody appears in serum. IgM anti-HBc Ag is a marker of acute or recent infection. IgG anti-HBc Ag indicates remote infection. Anti-HBs Ag : It is protective antibody. It is the only serological marker present after vaccination. After an infection, its presence indicates recovery and end of period of communicability. Anti-HBe Ag : Its presence indicate stopage of replication and low infectivity. HBV DNA : It is quantitative marker of HBV replication.