pathogens

• communicable diseases:

  • diseases that can SPREAD between organisms
  • caused by PATHOGENS, which are microorganisms that can invade and harm the body
• Types of pathogens

  • Bacteria
  • Viruses
  • Protists
  • Fungi
• Bacteria


  • Very small living cells that can reproduce rapidly inside your body
  • Can cause illness by producing poisins called TOXINS
• Viruses

  • Much smaller than bacteria, viruses are not cells
  • Invade and reproduce INSIDE body cells
  • Once the cell is full of viruses, it BURSTS and releases them to attack other cells
  • The damage to your cells during this process can make you feel unwell
• Protists

  • SINGLE-CELLED EUKARYOTES that can live as PARASITES, which means they may live on or inside other organisms and can cause harm
  • Often transferred to the host by a VECTOR, like a mosquito, which itself does not get the disease
• Fungi


  • Can be single-celled or multi-celled
  • Multi-celled fungi have a body made of HYPHAE; Structures that can cause infections by penetrating human skin or plant surfaces
  • Hyphae can produce SPORES which aid in their spread to other plants and animals