Tuberculosis

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Tuberculosis (TB) is a bacterial infection that is caused by the bacteria Mycobacterium tuberculosis.

Contents

Disease

MTB is transmitted via droplet nuclei when a person coughs or sneezes and is then inhaled by another individual. The MTB travels to the alveoli where it comes into contact with Macrophages that engulfs the MTB Pathogen. MTB evades the immune system by binding to mannose receptors and is phagocytosed where it secretes a protein that modifies the Phagosome to prevent Phagosome - Lysosome fusion thus preventing Antigen presentation. The MTB then multiplies within the Macrophage until it bursts. However, some MTB Antigen s are still presented which activate T-cells which then activate Cytokines including IFN. IFN causes activation of macrophages which can now destroy the MTB. This is a cell-mediated response and helps to control the infection but MTB can still multiply in inactivated macrophages and eventually spreads to the Bronchi where it can spread to the rest of the body - extrapulmonary tuberculosis [1][2][3].

TB is considered to be either 'Latent' or 'Active'. A patient with a latent TB infection will not experience any of the usual symptoms that are characteristic of tuberculosis and is unable to spread the infection to others. [4] According to the World Health Organisation, "the overall lifetime risk of developing active TB is about 10%" for a patient with a latent infection who is otherwise in a good state of general health. This risk of the infection becoming active increases in those with compromised immune systems, such as HIV patients and the elderly. [5] If TB becomes active then the infected patient will be symptomatic and contagious and must be treated.

At Risk:

Symptoms

Symptoms include:

Prevention

Treatment:

Two main antibiotics:

References

  1. https://www.tbfacts.org/tb/
  2. https://www.cdc.gov/tb/education/corecurr/pdf/chapter2.pdf
  3. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC164219/
  4. https://www.cdc.gov/tb/publications/factsheets/general/ltbiandactivetb.htm
  5. http://www.who.int/tb/areas-of-work/preventive-care/ltbi_faqs/en/
  6. Madigan M.,Martinko J.,Bender K.,Buckley D.,Stahl D. Brock Bology of Microorganisms, fourth edition (global edition)
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