3 Viruses Go "Viral"

Activity 1

Discussion

The purpose of this discussion is to have students consider the differences between infectious diseases and noninfectious diseases and what determines whether an infectious disease is considered contagious. The discussion should lead to students to considering the primary modes of transmission of infectious agents and contagious diseases.

You may want to initiate discussion with questions such as:

  • What is the difference between an infectious disease and a noninfectious disease?

    Students should recognize that infectious diseases are caused by pathogens such as viruses, bacteria, and parasites and can be spread by direct contact or through vectors. Noninfectious diseases cannot be “caught” from other humans or animals.

  • Food poisoning is generally categorized as an infectious disease because it is usually caused by bacteria (such as E. coli or Salmonella). However, you cannot infect other people with your food poisoning as you can infect them with measles. Why are food poisoning and measles both considered infectious diseases? Why is one considered contagious and the other not?

    Both are caused by infectious agents but only measles can be spread by indirect contact with an infected individual. Food poisoning cannot be "caught" by direct or indirect contact with another person with food poisoning.

  • Based on the Disease Chart, what are the major modes of transmission for infectious agents? What is the primary mode for contagious diseases?

    The primary modes of transmission for infectious agents include contact with infected individuals, aerosol of infected droplets, food-borne, water-borne and vector borne (such as through insects and animal bites). Students should recognize that contagious diseases are spread from person to person through direct contact with bodily fluids on a person or through sexual encounters. They are also spread by indirect contact through infected droplets in the air that are inhaled or on objects that individuals touch and then enable entry when they touch their mouth or nose.

Post-Discussion Activities

Based on the discussion about each kind of disease, have students develop a definition for an infectious disease and contagious disease. Their definitions should demonstrate an understanding that all contagious diseases are infectious diseases but not all infectious diseases are contagious by definition.

At this point you may want to assess student understanding of viral diseases and what kinds of diseases are contagious. Have students create a fictitious disease that includes the following information:

  1. A description of the symptoms of the disease
  2. The causative agent, its name and why it has that name (e.g. Ebola virus – named for a river in Africa)
  3. Mode of transmission (e.g. direct contact, airborne, foodborne, waterborne, animal/insect vector, animal reservoir)
  4. Is it contagious and if so, how contagious is it?

Have students (individuals or small groups) present their fictitious disease with information on a, b and c, and then have the class decide whether the disease is contagious or not and explain their decision.

  • What is the difference between an infectious disease and a noninfectious disease?
  • Food poisoning is generally categorized as an infectious disease because it is usually caused by bacteria (such as E. coli or Salmonella). However, you cannot infect other people with your food poisoning as you can infect them with measles. Why are food poisoning and measles both considered infectious diseases? Why is one considered contagious and the other not?
  • Based on the Disease Chart, what are the major modes of transmission for infectious agents? What is the primary mode for contagious diseases?