pathogens

• Pathogen


  Microorganism that causes disease
• Types of pathogens

  • Viruses
  • Bacteria
  • Fungi
  • Protists
• Pathogens in animals

  • HIV potentially leading to AIDS
  • Salmonella
  • Athlete's foot
  • Malaria
• Pathogens in plants

  • Tobacco mosaic virus
  • Agrobacterium
  • Rose black spot
  • Downy mildew
• All types of pathogen have a simple life cycle
• Pathogen life cycle


  • Infect a host
  • Reproduce themselves or replicate if it is a virus
  • Spread from their host
  • Infect other organisms
• Pathogens


  • Have structural adaptations that make them successful at completing their life cycles, which enable them to cause further disease
• Communicable diseases


  Diseases caused by pathogens that can be transferred from one person to another
• Other types of disease

  • Inherited genetic disorders like cystic fibrosis
  • Deficiency diseases caused by lack of essential vitamins or minerals, such as scurvy
  • Diseases like cancer that develop as a result of exposure to carcinogens or develop naturally as cell division occurs incorrectly
• All organisms are affected by pathogens
• Even bacteria are infected by certain types of virus
• Some pathogen infections can be transferred to organisms of a different species
• Ways pathogens can be transmitted

  • Direct contact
  • Water
  • Air
  • Unhygienic food preparation
  • Vector
• Direct contact transmission


  • Sexual contact during intercourse
  • Non-sexual contact, like shaking hands
• Water transmission


  • Dirty water can transmit many diseases, such as the cholera bacterium
• Air transmission


  • When a person who is infected by the common cold sneezes, they can spray thousands of tiny droplets containing virus particles to infect others
• Unhygienic food preparation transmission

  • Undercooked or reheated food can cause bacterial diseases like Escherichia coli which is a cause of food poisoning
• Vector


  Any organism that can spread a disease e.g mosquito with malaria