Viral Diseases

• How do viruses cause disease?

  They enter cells and replicate, causing cell damage
• What are the symptoms of measles?

  Fever and red skin rash
• How is measles spread?

  Through droplet infection
• What are the symptoms of HIV?

  Initially flu-like symptoms, leading to AIDS
• How is HIV spread?

  Through sexual contact or exchange of bodily fluids
• What are the symptoms of tobacco mosaic virus?

  Discolouration of leaves, reducing yield as the affected part of the plant cannot photosynthesise
• How is tobacco mosaic virus spread?

  Through contact between diseased and healthy plants
• How does HIV lead to AIDS?


  The virus attacks the immune system
• How HIV is being prevented: 


  Condoms, not sharing needles, mothers with HIV bottle feeding children instead of breastfeeding
• How development of AIDS is being prevented: 


  Use of antiretroviral drugs which stop the virus replicating in the body
• How is tobacco mosaic virus being prevented?


  Good field hygiene

  Pest control

  Growing TMV-resistant strains