Communicable Disease 2 - Viruses

• Viruses


  • Not cells, not living, but considered organisms
  • About 10,000 times smaller than animal cells
  • Can't reproduce by themselves, but can use a host cell's machinery to make copies of themselves
  • Can burst the host cell to release new viruses
• Viruses colonizing and bursting host cells


  Damages the body and makes us feel ill
• Viral diseases covered


  • Measles
  • HIV
  • Tobacco mosaic virus
• Measles virus


  • Spread by droplets when an infected person coughs or sneezes
  • Causes a red rash and fever
  • most young children are vaccinated against measles.
  • Rare in UK due to vaccination
• HIV


  • Spread by sexual contact or sharing bodily fluids
  • Causes a deficient immune system
  • Initially causes flu-like symptoms
  • Can develop into AIDS if left untreated
  • Can be managed with antiretroviral drugs
• Tobacco mosaic virus (TMV)


  • Affects plants, not humans
  • Causes discoloured patches on leaves, reducing photosynthesis and plant growth
• When using the term HIV, you're referring to the virus, not the disease
• AIDS is classed as a disease or syndrome in which the person's immune system can't cope anymore