Diseases

• Communicable diseases


  Diseases that can spread between organisms
• Viruses

  • Acellular
  • Have genetic material (RNA or DNA) but no organelles or nucleus
  • Cannot replicate without a host cell
• Viral diseases


  • HIV/AIDS (affects humans, spread through sexual contact)
  • Influenza (affects animals including humans)
  • Tobacco mosaic virus (affects plants)
• Protoctist diseases


  • Malaria (affects animals including humans, spread by a vector (mosquitos))
  • Potato (or tomato) late blight (affects potatoes or tomatoes, produces spores during reproduction that are spread in the air to other hosts)
• Fungal diseases


  • Black sigatoka (affects bananas)
  • Ringworm (affects cattle)
  • Athlete's foot (affects humans, spread by direct and indirect contact)
• Transmission


  • Direct transmission (directly from one organism to another, e.g. through infected droplets, sexual contact, touch)
  • Indirect transmission (from one organism to another via an intermediate, e.g. between animals or humans via a vector, spores, through the air or food)
• Climate affects transmission


  Having the ideal temperature for a vector to survive and reproduce
• Living conditions affect transmission

  • Overcrowding makes transmission easier
  • Poor hygiene practices e.g. not washing hands
• Social factors affect transmission

  • Lack of sexual education and hygiene education
  • Lack of good healthcare facilities and poor drug or vaccine availability
• Measures to decrease transmission

  • Mask wearing
  • Destroying vectors
  • Quarantine of infected individuals
  • Increasing hygiene practices e.g. hand washing
  • Restrict travel
• Bacterial diseases


  • Tuberculosis (TB) (affects animals including humans, spread via infected droplets)
  • Bacterial meningitis (affects humans)
  • Ring rot (affects potatoes and tomatoes)
• Vector

  An organism which carries a pathogen without getting symptoms of the disease