3.1.1 Communicable (infectious) diseases

• How do bacteria make us feel ill?

  ● Reproduce rapidly inside the body

  ● Produce toxins (poisons) that damage cells
• how do viruses make us feel ill?

  ● Live and replicate rapidly inside cells

  ● Causing cell damage eg. cell bursts
• How can pathogens be spread? Depends on the specific pathogen, but 3 broad ways:

  1. By direct contact eg. contact with contaminated surfaces / skin
  2. By water eg. by drinking / cooking with / bathing in
  3. By air eg. inhaling droplets from sneezes / coughs
• How can the spread of diseases be reduced or prevented?

  There are many different ways and these will again depend on the specific pathogen.

  Examples:

  ● Hygiene - eg. regular hand washing before preparing food, disinfecting surfaces

  ● Vaccination - to provide immunity

  ● Isolation - reduces contact with healthy people

  ● Destroy vectors (organisms that transport the pathogen) eg. using insecticides (kills insects)
• why is this statemnt wrong?

  “All microorganisms are pathogens / bad.”

  Not all microorganisms are pathogens as not all cause disease. Many bacteria live in your body, eg. in your gut, and are important for health.
• why is this statement wrong?

  “Viruses are cells.”

  Viruses are not cells. They live inside your cells and ‘hijack’ cell machinery to replicate themselves.
• why is this statement wrong?

  “A pathogen is a disease.”

  A pathogen is a microorganism that causes disease
• On aeroplanes, pathogens can easily spread from one person to another. Suggest one way this happens. (1)

  ● Through air / coughs / sneezes

  ● Touch of same surfaces / skin
• A fungus causes an infection called athlete’s foot. The fungus infects the skin and grows in moist, warm conditions. Describe how athlete's foot can be transmitted from one person to another. (2)

  ● Person with fungus walks barefoot (somewhere damp) / fungus left on shower floor

  ● Skin / foot of another person comes into contact with surface with fungus on
• A virus called RSV causes severe respiratory disease. Suggest two precautions that a person with RSV could take to reduce the spread of the virus to other people. (2)

  ● Regular hand washing / use hand sanitiser

  ● Cover nose / mouth when coughing / sneezing / wear a face mask

  ● Clean / disinfect / sterilise surfaces regularly
• What are pathogens?

  ● Microorganisms that cause infectious disease

  ● Examples - bacteria, viruses, protists or fungi

  Pathogens may infect plants or animals.