Pathogens and Disease

• What do Pathogens spread

  • Communicable diseases are spread from person to person - they are infectious 
  • Communicable diseases are spread by pathogens
• What are Pathogens

  Pathogens are microorganisms that cause infectious diseases (communicable)
• Examples of Pathogens

  • Bacteria 
  • Viruses 
  • Protists 
  • Fungi
• Bacteria causing food poisoning

  • Most people recover from food poisoning 
  • Sometimes it can be fatal 
  • Many bacterial diseases can kill us
• How bacteria make us ill

  • Once inside the human body, bacteria reproduce very rapidly 
  • Under ideal conditions, bacteria can divide every 20 minutes 
  • Bacteria can then release harmful chemicals called toxins 
  • These damage tissues and make us feel ill

  
• How viruses damage cells

  • Viruses cannot reproduce by themselves - They can only reproduce inside a host cell 
  • First the virus invades the host cell 
  • The virus then reproduces inside the host cell 
  • This is very damaging to the cell - When the virus leaves the cell it can cause the cell to burst open and die

  
• How pathogens are spread

  • In the air e.g. in water droplets (influenza) 
  • In water e.g. cholera 
  • Direct contact between individuals e.g. HIV 
  • Vectors
• What are vectors

  • Organisms that carry and pass on the pathogen without getting the disease
• How the spread of pathogens can be reduced

  • Simple hygiene measures : washing your hands before eating, and sneezing into a handkerchief  
  • Destroying vectors 
  • Isolating infected individuals so they cannot pass the pathogen on (e.g. in the case of ebola)
  • Giving people at risk a vaccination 
  • Providing people with clean drinking water  
  • Using a condom during sex reduces the spread of HIV
• What the UK does with their drinking water to prevent the spread of pathogens

  In the UK, drinking water contains chlorine which kills harmful microbes