Hepatitis B: Definition, Transmission & Surface Antibody

Instructor: Lori Haag

Lori has teaching experience in the health care setting. She has an associate's degree in Nursing and a bachelor's degree in Psychology.

In this lesson, you will learn about hepatitis B, types of infection, and modes of transmission. You will also learn about the hepatitis B surface antigen and its role in immunity to the disease.

Coming Soon to a Body Near You!

It creeps into your body and can lurk there for years. It can make you extremely sick if your body allows it to. Playing tricks on your immune system is one of its best defenses. It will thrive inside you and can survive outside your body for long periods of time, under harsh conditions and extreme temperatures. Its DNA has been found in the bodies of mummies over 400 years old. What is it? It is the hepatitis B virus, invading a body near you!

What is Hepatitis B?

Hepatitis B is a global health problem with approximately one-third of the world's population displaying evidence of current or past infection. Numbers are higher in developing countries where vaccinations are not routine. In the U.S. alone, nearly 60,000 new cases of hepatitis B emerge, and around 2 million people have a chronic infection.

The word hepatitis itself means inflammation of the liver. Toxins, drugs, and alcohol can all cause injury to the liver and impair its function. Hepatits B is a virus from a family of viral infections that affect the liver and can cause permanent damage to it such as cirrhosis and carcinoma (cancer).

Acute vs. Chronic Infection

The development of the disease and manifestation of symptoms are heavily dependent on both the virus and the body's reaction to it. Many factors come into play when considering the progression of the disease and why some people develop an acute (short -term) infection and for others it becomes chronic (long term). Age of exposure, concurrent disease processes, and immune response are all contributing factors in the development of the disease and subsequent liver involvement. For example, the earlier one becomes infected, the greater the risk chronic hepatitis B will develop. Babies who acquire hepatitis B at birth from their mother during delivery have a 90% chance of developing chronic hepatitis whereas transmission in adulthood poses only a 5% risk.

In acute hepatitis B, there is approximately a 2-4 week incubation period (although some statistics indicate 45-160 days) where a person will have no signs or symptoms of the disease but the virus is actively replicating inside the body. Once symptoms begin to manifest, the illness generally runs its course over a 3-4 week period before it begins to resolve and clear itself from the body. Clinical signs of hepatitis B become present more often in adults than infants and children, however 50% of adults show no signs at all. Fifty percent of adults fully recover after manifestations of active infection.

People with chronic hepatitis are often asymptomatic, and may never show any signs of illness. They are still capable of spreading the disease to others, however, and they are still susceptible to complications and liver involvement later in life. Twenty five percent of people with chronic hepatitis B infection will likely develop cirrhosis (scarring of the liver) or hepatocellular carcinoma (liver cancer).

Common signs and symptoms of an acute hepatitis B infection include:

  • Low-grade fever
  • Jaundice
  • Enlarged liver
  • Enlarged spleen


The hepatitis B virus is an extremely resistant virus that can withstand extreme temperatures and harsh conditions. It can live for up to seven days outside the human body at room temperature and up to fifteen years when stored at -20 degrees celsius. The liver of a 400 year old mummy in Korea was found to contain the hepatitis B virus. A unique feature contributing to its virulence, is its ability to trick the host's immune system by producing decoy antibodies. These decoy antibodies confuse the immune system and make the virus more difficult to fight.

Upon exposure to a virus, the body will produce antibodies against it. These antibodies are detectable in the blood. Hepatitis B surface antibodies, HBsAB provide immunity because the body can now recognize the virus and fight it. Presence of HBsAB can be the result of passive or active immunity immunity. Passive immunity occurs as a result of receiving the hepatitis B vaccine. Active immunity occurs after a previous hepatitis B infection.

Transmission and Risk

The hepatitis B virus is transmitted through blood, semen, and vaginal secretions. It is not transmitted through casual contact. Consequently, people who are often exposed to these bodily fluids are more likely to be infected than those who are not. High-risk populations include:

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