Mycobacterium tuberculosis and Mycobacterium bovis are bacteria that causes tuberculosis; it transmitted in aerosol (air born droplets) so can be transmitted by coughing, sneezing and spitting- providing some cells are breathed in. It can also be contracted from cows milk.
Risk of infection is increased by:
- Over crowded conditions
- Weak immune system
- Repeated contact with infect people
Course of infection
Primary infection:
- Bacteria enter the lungs and begin to multiply
- White blood cells go to attack them (engulfed by phagocytes) (encased in tubercle by macrophages)
- This inflames lymph nodes so they can't drain the lungs (causing cough)
- Often at this stage most bacteria are destroyed, but some may remain (dormant)
Post-primary infection:
- Years later the remaining bacteria cause a second infection (if immunosuppressed)
- They attack the epithelial cells- causing the infected person to cough it up damaged lung tissue
- The damage allows bacteria to enter the blood and spread to other organs
- The damage decreases the available surface area for gas exchange and makes the diffusion distance further, meaning sufferers will have reduced gas exchange
- Cough
- Fever
- Fatigue
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