Biology 4.4 Lung Disease - Pulmonary Tuberculosis

Tuberculosis = infectious disease, can affect any part of the body, usually found in the lungs.

Causes and symptoms

Caused by one of two species of rod-shaped bacteria = Mycobacterium tuberculosis or Mycobacterium bovis.

Symptoms initially include persistant cough, tiredness, loss of appetite leading to weightloss.

Fever and coughing up of blood may occur as disease develops.

Transmission

Spread through air by droplets, released into air when infected individuals cough, sneeze, laugh or talk.

M-tuberculosis = resistant bacterium, can survive several weeks when droplets have dried.

Takes close contact over period of time to transmit bacteria.

TB can be spread from cows to humans (M-bovis) and milk may contain bacterium.

Some people have greater risk of contracting TB:

• People in close contact with infected individuals over long periods of time e.g. living in overcrowded conditions.
• Work or reside in long-term car facilities where relatively large numbers of people live together.
• People from countries where TB is common.
• Those with reduced immunity: v. young or v.old, AIDS patients, people with medical conditions, those undergoing treatment with immunosuppressant drugs, malnourished, alcoholics or…