Hepatitis B is an inflammation of the liver caused by the hepatitis B virus (HBV). It can be either acute or chronic. The acute form of the disease typically resolves within a few weeks but can last for up to 6 months, while chronic hepatitis B can last for a lifetime. According to the World Health Organization (WHO), up to 90 percent of infants infected with HBV within their first year of life will develop chronic hepatitis B, and 30 to 50 percent of children infected before age 6 will develop it. Fewer than 5 percent of adults infected with HBV develop the chronic form of the disease.
Signs and Symptoms
Not everyone who becomes infected with HBV will develop symptoms, but adults and children over 5 years old are most likely to show signs of acute hepatitis B, according to the Centers for Disease Control and Prevention (CDC). About 70 percent of adults with acute hepatitis B develop symptoms, which can include: These symptoms appear, on average, from one to three months after exposure to the virus. Some people with chronic hepatitis B may have ongoing symptoms similar those of acute hepatitis B, but most people experience no symptoms for 20 years or more.
Hepatitis B Complications
In rare cases, acute hepatitis B can cause liver failure, leading to death. Although chronic hepatitis B often causes no symptoms, about 15 to 25 percent of people with the disease develop serious complications, according to the CDC. These include cirrhosis (scarring of the liver) and liver cancer. More than 780,000 people worldwide die from these complications each year, according to the WHO.
Diagnosing Hepatitis B
To determine whether you have hepatitis B, your doctor will first get your medical and symptom history and give you a physical examination. If your doctor suspects that you may have hepatitis B, he or she will order blood tests to diagnose your condition. It’s important to note that hepatitis B cannot be distinguished from other forms of hepatitis without laboratory tests. These tests, which may be done in a series called a panel, look for antigens and antibodies associated with hepatitis B. An antigen is a substance on the surface of a virus that causes an immune response such as the production of antibodies. Antibodies are substances that the body produces to attack and destroy viruses.
Blood Tests for Hepatitis B
If you test positive for the hepatitis B surface antigen (HBsAg), you have HBV in your blood. You have a chronic infection if you test positive for HBsAg consistently for at least 6 months. If you test negative for HBsAg but positive for the hepatitis B surface antibody (anti-HBs), you are protected from (immune to) HBV because you’ve received the vaccine or recovered from an acute infection. Another test to detect acute hepatitis B looks for the IgG antibody to hepatitis B core antigen (IgG anti-HBc). Testing positive for the antibody to this antigen — the hepatitis B core antibody (anti-HBc) —means either that you’re currently infected with HBV, or that you were in the past, depending on the results of the HBsAg and anti-HBs tests. The hepatitis B “e” antigen (HBeAg) can only be found in the blood during an active infection and signifies high levels of the virus (and, as a result, signifies being able to spread it easily to other people). On the other hand, having the hepatitis B “e” antibody (HBeAb or anti-HBe) means that you have chronic hepatitis B but low levels of the virus, and thus a lower risk of complications. Unlike these antigen and antibody tests, the hepatitis B viral DNA test can directly detect the presence of the virus’s DNA in your blood. Remember that only your doctor can interpret the results of your tests.
