TB

• transmitted by droplet infection
• droplet infection 


  passed on through air
• how is TB spread 


  bacterium enters lungs

  triggers inflammatory response and is engulfed by macrophage

  bacterium closed in a phagosome

  bacterium proliferates which destroys macrophage
• Primary TB 


  after 3 weeks of being exposed cell mediated immunity occurs

  immune cells surround infected macrophage

  prevent TB from spreading

  macrophage in the centre die (caseous necrosis)

  TB dies off or remains dormant
• active TB 


  when TB is reactivated bacterium can spread to other parts of the body

  memory T killer cells released

  more caseous necrosis formed

  TB can spread to other organs through lymphatic system