Pulmonary Tuberculosis (TB)

TB is caused by two species of rod-shaped bacteria. Transmission is spread through the air by droplets, released into the air when infected individuals cough, sneeze, laugh or talk. One species of the bacterium can survive several weeks once the droplets have dried. TB involves close contact with an infected person over a period of time. TB is therefore likely to be spread between family, colleagues and in crowded conditions with poor ventilation. Certain groups of people are more at risk:

• those in close contact with infected people over long periods
• work or live in long term care facilities where large numbers of people live close together
• from countries where TB is common > spread easier
• have reduced immunity; young, old, with AIDS, underlying health, malnourished, alcoholics, drug users, homeless and those following transplant surgery > still need same close contact with those with TB but the time taken to catch is less and it is more likely for them to catch
  

Once the bacterium have been inhaled by someone not immune, the infection takes the following course;

• bacteria grow and divide within the upper regions of the lungs where there is a plenty supply of oxygen
• the body's immune system responds and WBCs accumulate at the site of infection to ingest the bacteria
• this leads to inflammation and the enlargement of lymph nodes, this is called primary infection and usually occurs in children
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