175 Healthcare: Biological Hazards

TB-Related Conditions

Not everyone infected with TB bacteria becomes sick. As a result, two TB-related conditions exist:

Latent TB Infection

TB bacteria can live in the body without causing sickness. This condition is called latent TB infection (LTBI). In most people who breathe in TB bacteria and become infected, the body is able to fight the bacteria.

Many people who have LTBI never develop TB disease. In these people, the TB bacteria remain inactive for a lifetime without causing disease. But in other people, especially people who have a weak immune system, the bacteria become active, multiply, and can cause TB disease.

Health care personnel should be screened for TB upon hire, also known as pre-placement. Annual TB testing is not recommended unless there is a known exposure or ongoing transmission.

TB Disease

TB bacteria becomes active if the immune system can't stop them from growing. When TB bacteria are active (multiplying in your body), this is called TB disease. People with TB disease are sick. They may also be able to spread the bacteria to people they spend time with every day.

Many people who have latent TB infection never develop TB disease. Some people develop TB disease soon after becoming infected (within weeks) before their immune system can fight the TB bacteria. Other people may get sick years later when their immune system becomes weak for another reason.

A positive TB test only tells that a person has been infected with TB bacteria. It does not tell whether the person has LTBI or has progressed to TB disease.

For people whose immune systems are weak, especially those with HIV infection, the risk of developing TB disease is much higher than for people with normal immune systems.

Click on the image on the right. It compares the symptoms between LTBI and TB disease.

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