. Hepatitis B Virus (HBV) is a highly contagious virus that infects the liver, causing inflammation and potentially leading to chronic liver disease, cirrhosis, or liver cancer.
. It is transmitted through contact with infected blood, sexual contact, sharing needles, from an infected mother to her baby during childbirth, and through contaminated medical equipment or blood transfusions.
. Symptoms of HBV infection include fatigue, jaundice, dark urine, pale stools, abdominal pain, and nausea, although many infections, especially in early stages, are asymptomatic.
. HBsAg is a protein on the surface of the HBV that is the first detectable marker during an acute infection.
. The presence of HBsAg indicates an active infection and is used to diagnose both acute and chronic infections. It helps differentiate between acute infection, chronic infection, and recovery from Hepatitis B.
. In chronic infections, the persistence of HBsAg for more than six months suggests a chronic carrier state and indicates the need for further monitoring and possible antiviral treatment.
. HBsAg is crucial in screening for HBV in high-risk populations, such as pregnant women, healthcare workers, and blood donors. If HBsAg is absent, it typically indicates that the individual is either immune (due to vaccination or prior infection) or has cleared the virus.
Note: HBsAg is not a standalone test for diagnosing HBV infection. It should be interpreted alongside other tests, such as HBcAb, HBc IgM, HBV DNA, and liver function tests, for a comprehensive assessment.