Australia Antigen: Symptoms & Treatment

Australia Antigen: Symptoms & Treatment
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  • 0:00 Definition
  • 0:35 Hepatitis B
  • 1:45 Symptoms
  • 2:56 Treatment
  • 3:57 Lesson Summary
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Lesson Transcript
Instructor: Danielle Haak

Danielle has a PhD in Natural Resource Sciences and a MSc in Biological Sciences

The Australia antigen is associated with the hepatitis B virus and is one of the antigens used to diagnose a hepatitis B infection. Learn more about it in this lesson, as well as corresponding symptoms and possible treatment options.


An antigen is a piece of a virus that can be found in the blood and often causes the immune system to respond to an infection. The Australia antigen is a specific antigen used to diagnose patients with the hepatitis B virus. It got its name because it was first found in an Australian aborigine, but now we know it appears in anyone with hepatitis B. To understand this antigen's role, it's useful to first know more about hepatitis B.

Hepatitis B

Hepatitis B can be characterized as acute or chronic. Acute hepatitis B occurs shortly after infection and can often be cured during this period. Conversely, chronic hepatitis B is an infection that lasts longer than six months. At this point, it is unlikely the patient will ever be completely cured. The good news is that it's relatively rare for adults to develop chronic hepatitis B, though it is more common in children.

Interestingly, not all adults who develop chronic hepatitis display symptoms; rather, they are carriers of the virus without obvious signs of infection. Those who do develop symptoms most often experience liver disease that can become life threatening. The hepatitis B virus is spread through contact with blood or blood-contaminated fluids.

The Australia antigen is commonly found in hepatitis B carriers in the tropics, and once the link between this antigen and hepatitis B was realized, a reliable vaccine was developed, and testing for hepatitis B became easier.


Not all people with the Australia antigen develop symptoms of hepatitis B. However, if symptoms of hepatitis B occur, they most often include a loss of appetite, fatigue, nausea and vomiting, localized pain in the mid-section near the liver, itching, jaundice, dehydration, and discolored urine and fecal matter. If the Australia antigen appears in blood analysis, it may be a signal that the virus is actively reproducing in the body. This is an area of active ongoing research.

Cases of chronic hepatitis B that cause symptoms indicate the liver is infected and no longer functioning properly. This can cause the body to retain fluids, causing swelling, as well as weight gain or weight loss, jaundice, vomiting, bleeding from orifices, and hepatic encephalopathy, which is characterized by extreme fatigue, confusion, and even coma. Serious cases also cause cirrhosis, which is excessive scarring of the liver than can affect function, or liver cancer.

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