Tuberculosis

Tuberculosis (TB) is a chronic infectious disease that primarily affects the lungs. In many patients, TB causes no symptoms while in others it is fatal.

Causes

TB is a bacterial infection caused by Mycobacterium Tuberculosis. When someone with active TB of the throat or lungs coughs or sneezes, people nearby may inhale the bacteria. TB is easily spread in crowded conditions, and among people who are ill or have weakened immune systems.

Risk Factors

A risk factor is something that increases your chance of getting a disease or condition.
People who have weakened immune systems or chronic diseases are at highest risk for developing active TB. These include:
  • HIV infection
  • Malnutrition
  • IV drug use
  • Alcoholism
  • Leukemia, lymphoma and other cancers
  • Poorly controlled diabetes
  • Severe kidney disease
  • Suppressed immune system caused by medications, such as drugs to prevent rejection of a transplanted organ
  • Other risks factors include:
  • Silicosis (an occupational lung disease)
  • Living in crowded, indoor conditions, such as:
    • Homeless shelters
    • Dormitories
    • Military barracks
  • Age: Infants, young children, and elderly people

Symptoms

Most people infected with TB have no symptoms. The bacteria lie dormant in the lungs and may remain there permanently without causing illness. During the dormant stage, the infected person cannot spread TB to others. Once the bacteria become active, the infection can be easily spread.
Symptoms of active TB include:
  • Severe cough that lasts more than 2 weeks
  • Coughing up blood and sputum (mucus from deep in the lungs)
  • Pain in the chest
  • Weakness or fatigue
  • Unexplained weight loss
  • Chills
  • Fever
  • Night sweats
  • Loss of appetite

Diagnosis

A skin test is used to screen for inactive TB. A small amount of tuberculin test fluid is injected into the skin of the lower part of your arm. The test is positive if after 2-3 days, a raised, red welt appears at the injection site that is 10 mm or greater in diameter. (Under some circumstances the cut-off may be 5 or 15 mm.) This means you were exposed to TB at some point, even if you never became ill. Your doctor will then order a chest x-ray to look for signs of lung infection. People at high risk of TB should be screened regularly, if and until they test positive.
If you have symptoms of active TB, you will have:
  • A chest x-ray
  • Samples of your sputum tested for the bacterium

Treatment

Medication can prevent TB from becoming active and cure active TB. It is extremely important that you take ALL medication exactly as prescribed. You must take all the medication, even if the symptoms go away. If you do not finish your medication, you may develop drug-resistant TB, which is extremely difficult to cure.
For Inactive TB:
People who have a positive tuberculin skin reaction need to take medication. Usually the drug isoniazid (INH) is prescribed for at least 6 months.
For Active TB:
Your doctor will prescribe a combination of the following drugs:
  • Isoniazid (INH)
  • Rifampin
  • Pyrazinamide
  • Ethambutol
  • Streptomycin
If you have active TB, you will need to be isolated from friends family and co-workers for the first several weeks of medication use. This helps prevent the spread of TB. After taking medication for several weeks, you can resume normal activity. You will need to keep taking the drugs for up to 2 years.

Prevention

If you have a positive skin test, you may prevent active TB from developing by taking medication (see above). There is a vaccine for TB that has the same effect, but it is not routinely used in the United States.
If you have active TB, you can prevent its spread by:
  • Avoiding contact with people during the first weeks of taking medication
  • Taking all medication as prescribed