3.1.1 Introduction to Communicable Diseases

• List the four types of pathogen:

  Bacteria, fungi, protists and viruses.
• What is a pathogen?

  A microorganism that causes disease.
• Do pathogens cause communicable or non-communicable diseases?

  Pathogens cause communicable diseases.
• Do pathogens infect animals, plants, or both?

  Both.
• What are the four main ways pathogens can spread and some examples?

  1. Through the air - Diseases such as influenza and measles can spread via tiny droplets of saliva that we expel when we cough or sneeze.
  2. Contaminated water - Diseases such as cholera can spread through water sources contaminated by the diarrhoea of infected people.
  3. Contaminated food - Diseases such as salmonella are spread by eating food which has been infected with salmonella, and then not cooked properly.
  4. Direct contact - Athlete's foot is spread by walking barefoot on surfaces contaminated with the fungi.
• What are the four main ways the spread of infectious disease can be prevented?

  1. Improved hygiene, such as washing hands and cleaning surfaces.
  2. Vaccination.
  3. Killing the vectors that carry pathogens.
  4. Isolating or quarantining people who are infected.
• Which two pathogens reproduce rapidly inside the body?

  Bacteria and viruses.
• Which pathogen may produce poisons called toxins that damage tissues and make us feel ill?

  Bacteria.
• Which pathogens reproduce inside cells and cause cell damage?

  Viruses.
• What is a microorganism?

  An organism that is of microscopic size and is either single-celled or made up of a colony of cells.
• What is the immune system?

  The body’s defence mechanism against disease.