Active Tuberculosis

What Is Active Tuberculosis?

Tuberculosis (TB) is a chronic bacterial infection caused by Mycobacterium tuberculosis. It is spread through the air and usually infects the lungs, although other organs and parts of the body can be involved as well.

 

Most people who are infected with tuberculosis harbor the tuberculosis bacterium without any tuberculosis symptoms. This is known as latent tuberculosis.

 

If the body's resistance is low because of aging, malnutrition, infections such as HIV, or other reasons, the bacteria may break out of hiding and cause active tuberculosis.

 

Impact of Active Tuberculosis

According to World Health Organization (WHO) estimates, each year, 8 million people worldwide develop active tuberculosis and nearly 2 million die. One in 10 people who are infected with tuberculosis bacteria may develop active tuberculosis at some time in their lives. The risk of developing active tuberculosis is greatest in the first year after infection, but active tuberculosis often does not occur until many years later.

 

Active Tuberculosis and the Immune System

TB bacteria become active if the immune system can't stop them from growing. The active bacteria begin to multiply in the body and cause active tuberculosis. The bacteria attack the body and destroy tissue. If this occurs in the lungs, the bacteria can actually create a hole in the lung.

 

Some people develop active tuberculosis soon after becoming infected, before their immune system can fight the TB bacteria. Other people may develop active tuberculosis later, when their immune system becomes weak for another reason.

 

Babies and young children often have weak immune systems. People infected with HIV, the virus that causes AIDS, also have very weak immune systems. Other people can have weak immune systems, too, especially people with any of these conditions: