HIV and TB

• what is tuberculosis


  contagious disease caused by bacterium - Mycobacterium tuberculosis
• what is the most common form of TB?


  respiratory or pulmonary
• what does it affect

  the lungs and is highly contagious
• why was there a decline in the number of cases ?


  improved housing and living conditions + development of antibiotics
• what % of people closely exposed to TB will become infected?


  30%
• when may infection occur? and why?

  when bacteria is inhaled and lodge in the lungs. the bacteria then multiply in the lungs
• what are the two phases of the disease

  primary infection (first phase) and active tuberculosis (second phase)
• how long can the first phase last?


  several months and may have no symptoms
• what does TB cause from a host's immune system? 


  inflammatory response
• what happens after the inflammatory response?


  macrophages engulf the bacteria
• what is formed after englufing by macrophages?


  granuloma - in TB these tissue masses are called tubercules - they are anaerobic and have dead bacteria and macrophages in the middle
• what happens after 3-8 weeks?


  infection is controlled and infected region of the lung heals
• when does primary infectiton happen most

  in childhood and heal without being noticed 90% of the time
• what happens in tuberculosis when engulfed by macrophages?


  TB bacteria can survive inside macrophages which is what makes it different to other infections
• what happens when TB bacteria is taken up by phagocytosis?


  once inside they resist the killing mechanisms used by these cells