What is tuberculosis?

Tuberculosis, or TB, is primarily an airborne disease caused by the bacteria, M. tuberculosis. The bacteria are spread through the air and usually infect the lungs, but can also infect other parts of the body as well.

One-third of the world’s population, nearly 2 billion people, is infected with M. tuberculosis, the TB bacterium. Although TB was once the leading cause of death in the United States, cases of TB declined rapidly in the 1940s and 1950s, once scientists discovered the first of several drugs used to treat the disease. Today, the incidence of TB in the US is the lowest ever. However, case rates among foreign born persons living in the US now accounts for most of the reported cases.

TB can be spread when a person with active pulmonary TB disease coughs, sneezes, talks, sings or laughs. Only people with an active pulmonary infection are contagious. Most people who breathe in TB bacteria are able to fight the bacteria and stop it from growing. The bacterium becomes inactive in these individuals, and is referred to as a latent TB infection. Approximately 10% of the US population has latent infection.

Although the bacteria are inactive, they still remain alive in the body, and can become active later. Some people can have a latent TB infection for a lifetime, without it ever becoming active and developing into TB disease. However, TB can become active if the immune system becomes weakened and cannot stop them from growing. This is when the latent TB infection becomes a TB disease.

What are the symptoms of TB?

Those people with inactive TB do not exhibit symptoms; however, they may have a positive skin reaction test. The tuberculin skin test has low specificity but three are newer tests that are more specific for M. tuberculosis. The CDC has recently established guidelines for these new blood tests.

Those with TB disease, however, can exhibit any of the following symptoms:

  • Bad cough (lasting longer than 2 weeks)
  • Pain in the chest
  • Coughing up blood or sputum
  • Fatigue or weakness
  • Loss of appetite
  • Weight loss
  • Chills
  • Fevers
  • Night sweats

How do I know if I should get tested for TB?

If you feel that you should be tested, a skin test will determine if you have a latent TB infection. There is also a blood test available to determine infection with TB. You should consider a skin test or blood test if:

  • You are a resident or employee in group settings where the risk is high (i.e. correctional facilities, hospices, skilled nursing facilities and other health care facilities)
  • You work in a mycobacteriology laboratory
  • You have been in contact with a person known or suspected to have TB disease
  • Your body’s resistance to illness is low, due to aging, malnutrition, HIV or other conditions that weaken the immune system
  • You think you might already have TB disease and are experiencing symptoms that are characteristic of TB disease
  • You are from a country or lived in a country where TB disease is prevalent, such as Africa, Asia, Eastern Europe, Russia, the Caribbean, and most countries in Latin America
  • You live or have been present in a facility where TB is common, such as in a crowded shelter, prison, and/or long-term care facility
  • You have used injected illicit drugs

Can TB be cured?

The good news is, yes, TB can be cured – even in people with HIV infection. However, you must take all of the medication as your doctor instructs you to do, or else not all of the bacteria will be killed.

Can TB be prevented?

Yes. You usually have to be in contact with someone with active TB for a long time before becoming infected. The most important measure to prevent the transmission of TB in the hospital is to have proper ventilation and/or proper personal protective equipment (respirator).

Where can I learn more?

CDC Hotline: 1.800.232.4636

© Copyright 1995-2010 The Cleveland Clinic Foundation. All rights reserved.

This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or health care provider. Please consult your health care provider for advice about a specific medical condition. This document was last reviewed on: 1/26/2010...#11301