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Infectious diseases

Infectious diseases. What is a pathogen?. What is a pathogen?. Pathogen- from Greek pathos (emotion/suffering) ; gene – to give birth to An agent causing illness or disease in the host/ an infectious particle able to produce disease. Are all pathogens infectious?. Not necessarily.

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Infectious diseases

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  1. Infectious diseases

  2. What is a pathogen?

  3. What is a pathogen? Pathogen- from Greek pathos(emotion/suffering); gene – to give birth to An agent causing illness or disease in the host/ an infectious particle able to produce disease

  4. Are all pathogens infectious? • Not necessarily

  5. Infectious agents • Pathogenic bacteria • Pathogenic viruses (not considered organisms) • Pathogenic fungi • Pathogenic protists (protozoa) • Pathogenic parasites – e.g. helminth worms • Pathogenic prion (not organisms)

  6. What are the top ten infectious diseases? 10. Smallpox 9. Typhoid 8. Influenza 7. Bubonic Plague 6. Cholera 5. Anthrax 4. Malaria 3. SARS Coronavirus 2. EBOLA or Nantahaemorrhagic virus 1. HIV

  7. WHO

  8. Non-specific defences: External Defences

  9. Innate Immunity: commensal (non-pathogenic) bacteria • Of the 100 billioncells in our bodies, only 10 billion are actually human cells! • The rest are commensal bactseria, fungi, protozoa and even arhropods! • They perform essential housekeeping functions in our bodies…

  10. Summary of external defences Anatomical Defences • skin • mucous membranes Body secretions/excretions • mucous • tears, saliva, urine (wash-out) • lysozyme in tears/nose/saliva • lactoperoxidase in breast milk • Acidic pH (sweat, urine, gastric fluid, vaginal secretions) • Zinc and spermine in semen Normal commensal flora • Inhibitory substances • Compete for nutrients Cilia Mucociliary escalator in respiratory tract

  11. Cells of the innate Immune System • Phagocytes – monocytes, macrophages and neutrophils (polymorphonuclear neutrophils) • Natural Killer Cells • Dendritic Cells

  12. Phagocytes

  13. Macrophages

  14. Neutrophils • Most common type of white blood cell (50 – 70%) • Phagocytic – but die immediately! • First immune cells to reach a site of infection – attracted by chemotaxis • PUS is made of dead neutrophils (that’s what makes pus white…)

  15. Phagocytosis (1)

  16. Phagocytosis (2)

  17. Natural Killer Cells The NK releases "perforin" molecules onto the target cell, which punches holes in its plasma membrane. The NK cell then releases cytotoxins which will induce apoptosis (programmed cell death) in the target cell. Nasty!! )

  18. Dendritic Cells

  19. A dendritic cell slide show… • Dendritic Cells are beautiful...

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