Tuberculosis its causes and Diagnosis

Spread of TB

Since TB is caused by bacteria, a person infected with the TB bacteria in his upper airways can cause spread of infection to other people. A person can become infected with tuberculosis bacteria when he or she inhales minute particles of infected sputum from the air. The bacteria get into the air when someone who has a tuberculosis lung infection coughs, sneezes, shouts, or spits. People who are nearby can then possibly breathe the bacteria into their lungs. You don’t get TB by just touching the clothes or shaking the hands of someone who is infected. Tuberculosis is spread (transmitted) primarily from person to person by breathing infected air during close contact. The bacteria can settle in people’s lungs and it begins to grow. From the lungs, the bacteria can move through the body fluids such as blood or lymphatic system to other parts of the body such as the kidney, spine and brain. TB in the upper airways can spread to other people and is classified as infectious. However, TB in other parts of the body does not spread through coughing or sneezing and hence is not considered an airborne infection.

Active and Dormant TB

Only a small percentage of people infected with TB develop active TB disease while the others are said to have sleeping or dormant TB. Active TB causes symptoms and makes the person feel sick


Medications can help reduce the risk of a person with dormant TB developing active TB. Only people with active TB can cause spread of infection to other people.



It may take many months from the time the infection initially gets into the lungs until symptoms develop. The usual symptoms that occur with an active TB infection are:


If the infection in the lung worsens, then further symptoms can develop which include:

  • Coughing
  • Chest pain
  • Coughing up of sputum (material from the lungs) and/or blood
  • Shortness of breath.
  • If the infection spreads beyond the lungs, the symptoms will depend upon the organs involved.


Who are at risk?

Anyone can get TB, but certain people are at higher risk, including:

  • People who live with individuals who have an active TB infection
  • Poor or homeless people
  • People living in overcrowded conditions
  • People with poor immunity
  • Nursing-home residents



If you have any of the above symptoms visit your doctor. If your doctor thinks you have been infected with the TB, a skin test can be done. The tuberculin skin test (Mantoux test) is one of the tests that can show if you are likely to have been infected. A new blood test called Quantiferon TB Gold is now also available. Other tests include chest X-ray and a sputum test.

You should be tested if you:

  • Live or work closely with someone who has been diagnosed with active TB of the lungs
  • Are infected with HIV


If you have TB infection, your doctor may prescribe a course of tablets and follow up with regular chest x-rays. Active TB disease can be treated with medication.  It will take at least six months to cure TB, sometimes longer. It is very important that you take the full course of treatment. If you don’t, TB can return and may be harder to cure because it may become resistant to the medication.


TB vaccine

The vaccine against TB is called BCG. It offers some protection from developing active tuberculosis, especially in infants and children.

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