Tuberculosis, also called TB, is an infection caused by a bacteria called Mycobacterium tuberculosis. It can affect any organ in the body but most commonly affects the lungs.
What is going on in the body?
TB is spread person to person when the bacteria is coughed into the air by one person and is inhaled by another person. In most people, the immune system, which is the body's defense against germs and other invaders, is able to control the infection. In these cases, the infection may cause few or no symptoms. Children younger than age 4, teenagers, elderly people, and those who have problems with their immune systems may develop a more severe infection. Severe infections can occur in every part of the body, including the brain. Tuberculosis is a common cause of death in the rest of the world, though death is rare in the US.
What are the causes and risks of the infection?
Exposure to a person with tuberculosis is the cause of the infection. Certain populations in the US are at a high risk of getting and spreading the infection. These "high-risk" populations include:
- the poor and homeless
- those who abuse alcohol or drugs
- people with weakened immune systems, such as those with AIDS
- people from less developed countries where tuberculosis is more common
What can be done to prevent the infection?
Avoidance of those with tuberculosis can prevent this infection, but is often not possible. Serious infections can sometimes be prevented when drugs are given after the initial infection but before serious disease develops.
How is the infection diagnosed?
This infection can often be diagnosed with a skin test. Sometimes people with immune problems and young children may not show positive skin test results but they still have this infection. In these situations, coughed-up phlegm, fluid from the stomach, or a tissue specimen from an involved organ such as a lymph node will reveal the bacteria. Special stains are used to allow the bacteria to be seen with a microscope. A special lab test that detects the bacteria's genes may also be used.
Long Term Effects
What are the long-term effects of the infection?
Severe infection can result in permanent organ damage, such as brain damage, or even death.
What are the risks to others?
This infection can be spread to other people in some cases.
What are the treatments for the infection?
Tuberculosis is treated with a combination of drugs. Isoniazid (i.e., INH), rifampin (i.e., Rifadin, Rimactane), pyrazinamide (i.e., PZA), ethambutol (i.e., Myambutol), rifabutin (i.e., Mycobutin), Rifapentine (i.e., Priftin) and streptomycin are some of the drugs used.
The number of drugs used and the choice of drugs may vary. This depends on the seriousness of the infection and the likelihood that the bacteria have become drug-resistant.
Treatment is usually started with three or four drugs, which may change later in therapy. It is important that the person be monitored to see what drugs work best. Treatment usually lasts between 6 and 12 months.
What are the side effects of the treatments?
The drugs used for tuberculosis have a number of side effects ranging from nausea and vomiting to problems with vision and the liver. The specific side effects depend on the drugs prescribed.
The main side effect of isoniazid, one of the most commonly used drugs, is liver damage. The risk of this side effect appears to increase with age.
What happens after treatment for the infection?
Most people improve and can return to normal activity. Often the infection is not considered cured, but rather, controlled. The infection can reactivate in the future and cause symptoms again. However, treatment generally prevents a person from spreading the infection to others.