Hepatitis B surface antigen (HBsAg) is a blood test ordered to determine if someone is infected with the hepatitis B virus. If it is found, along with specific antibodies, it means the person has a hepatitis B infection. If your blood is positive for HBsAg, it means you are infectious for the virus and can pass it to other people through your blood or body fluids.
Hepatitis B is a serious liver infection caused by the hepatitis B virus (HBV). For some people, hepatitis B infection becomes chronic, meaning it lasts more than six months. Having chronic hepatitis B increases your risk of developing liver failure, liver cancer or cirrhosis—a condition that causes permanent scarring of the liver.
Most people infected with hepatitis B as adults recover fully, even if their signs and symptoms are severe. Infants and children are more likely to develop a chronic hepatitis B infection. A vaccine can prevent hepatitis B, but there’s no cure if you have it. If you’re infected, taking certain precautions can help prevent spreading HBV to others.
Signs and symptoms of hepatitis B, ranging from mild to severe, usually appear about one to four months after you’ve been infected. They may include:
The Hepatitis B virus is passed from person to person through blood, semen or other body fluids.
Common ways HBV is transmitted include: