Tuberculosis (TB)

Q: What is TB? How does it spread? How is it treated?

A: Tuberculosis (TB) is a contagious lung disease that spreads through the air. When people with the disease cough, sneeze, talk or spit, they propel TB germs, known as bacilli, into the air. Only a small number of the bacilli need to be inhaled to cause an infection. However, not all people infected with TB bacilli will become sick. The immune system either kills the germs, or "walls off" the TB bacilli where they can lie dormant for years. Failure of the immune system to control infection with TB bacilli leads to active disease, when TB bacilli multiply and cause damage in the body. Left untreated, each person with infectious TB will spread the germs to about 10 to 15 people every year.

  • Someone in the world is newly infected with TB bacilli every second.
  • Overall, one third of the world's population is currently infected with TB.
  • 5% to 10% of people who are infected with TB become actively sick.

When a person with infectious TB is identified (using a microscope to look for bacilli in a sample of a person's sputum), a full course of the correct dosage of anti-TB medicines should be started, with support of health and community workers or trained volunteers. The most common anti-TB medicines are isoniazid, rifampicin, pyrazinamide and ethambutol.
Supervised treatment helps to ensure that an infected person completes the course of medicine to cure TB and prevent its further spread. Treatment must be continued regularly and uninterrupted for six to eight months. The internationally recommended approach to TB control is DOTS, which is a cost-effective public health strategy to identify and cure TB patients. The approach will prevent millions of TB cases and deaths over the coming decade.

 What are Tuberculosis Symptoms

You may not notice any symptoms of illness until the disease is quite advanced. Even then the symptoms -- loss of weight, loss of energy, poor appetite, fever, a productive cough, and night sweats -- might easily be blamed on another disease.

  • Only about 10% of people infected with M. tuberculosis ever develop tuberculosis disease. Many of those who suffer TB do so in the first few years following infection, but the bacillus may lie dormant in the body for decades.
  • Although most initial infections have no symptoms and people overcome them, they may develop fever, dry cough, and abnormalities that may be seen on a chest X-ray.
    • Pulmonary tuberculosis frequently goes away by itself, but in 50%-60% of cases, the disease can return.
  • Tuberculous pleuritis may occur in 10% of people who have the lung disease from tuberculosis.
    • The pleural disease occurs from the rupture of a diseased area into the pleural space, the space between the lung and the lining of the abdominal cavity.These people have a nonproductive cough, chest pain, and fever. The disease may go away and then come back at a later date.
  • In a minority of people with weakened immune systems, TB bacteria may spread through their blood to various parts of the body.
    • Cough and difficulty breathing are less common.
  • Generally, return of dormant tuberculosis infection occurs in the upper lungs. Symptoms include
    • common cough with a progressive increase in production of mucus and
    • coughing up blood.
    • Other symptoms include the following:
      • fever,
      • loss of appetite,
      • weight loss, and
  • About 15% of people may develop tuberculosis in an organ other than their lungs. About 25% of these people usually had known TB with inadequate treatment. The most common sites include the following:

When to Seek Medical Care

If someone among your family or close associates is found to be sick with active TB, you should see your doctor and be tested for tuberculosis.

  • The dangerous contact time is before treatment. However, once treatment with drugs starts, the sick person is noncontagious within a few weeks.
  • If you develop any side effects from medications prescribed to treat tuberculosis -- such as itching, change in color of skin, tiredness, visual changes, or excessive fatigue -- call your doctor immediately.

To view the TB factsheet click here

Testing for TB Infection

Tuberculosis (TB) is a disease that is spread through the air from one person to another. There are two kinds of tests that are used to determine if a person has been infected with TB bacteria: The tuberculin skin test and TB blood tests. To read more about TB testing click here>>