Epidemiological markers of Hepatitis – B is
**Core Concept**
Hepatitis B is a viral infection that affects the liver, and its epidemiological markers are crucial for understanding the spread and prevalence of the disease. The correct answer will reveal a key indicator used in public health to track the spread of Hepatitis B.
**Why the Correct Answer is Right**
Hepatitis B surface antigen (HBsAg) is a protein on the surface of the Hepatitis B virus. The presence of HBsAg in the blood indicates that the person is infected with the virus. This antigen is the primary marker used to diagnose Hepatitis B infection. It is produced early in the course of the disease and persists in the blood even after the person becomes immune. HBsAg is a critical marker for epidemiological surveillance, allowing health officials to track the spread of the disease and implement control measures.
**Why Each Wrong Option is Incorrect**
**Option A:** HBsAb (Hepatitis B surface antibody) is an antibody produced in response to Hepatitis B infection. While it is a useful marker for immunity against Hepatitis B, it is not the primary marker for diagnosing active infection.
**Option B:** HBeAg (Hepatitis B e-antigen) is a marker of viral replication and infectivity. While it is an important marker for understanding the disease, it is not the primary marker for epidemiological surveillance.
**Option C:** Anti-HBc (Antibody to Hepatitis B core antigen) is a marker of current or past infection. While it is useful for diagnosing Hepatitis B, it is not the primary marker for epidemiological surveillance.
**Clinical Pearl / High-Yield Fact**
The presence of HBsAg in the blood is a critical indicator of Hepatitis B infection. It is essential to remember that HBsAg persists even after the person becomes immune, making it a reliable marker for epidemiological surveillance.
**Correct Answer: A. HBsAg**