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Author(s): Nancy Moreno, PhD, Barbara Tharp, MS, Deanne Erdmann, MS, Sonia Rahmati Clayton, PhD, and James Denk, MA.

Microbes and Disease

Organisms that cause diseases are called “pathogens,” from the Greek word pathos, or suffering. Most pathogens are microbes, such as bacteria, protozoa, fungi or viruses. Sometimes, we call these tiny pathogens “germs.” Pathogens cause communicable, or infectious, diseases (diseases that can spread from one organism to another). Some diseases are harder to catch than others, because different pathogens are transferred from one organism to another in different ways (through droplets in air or in fluids, through contact with a surface containing the pathogen, from insect bites, etc.). Some pathogens can make you a lot sicker than others, and some can kill.

A widespread outbreak of a disease is called an “epidemic.” An epidemic that spreads broadly throughout the world is referred to as a “pandemic.” This activity highlights six microbe-based diseases with major global historical impacts: cholera, plague, malaria, smallpox, HIV/AIDS and tuberculosis. 

Of course, microbes do not cause all diseases. Invertebrates, such as hookworms, tapeworms, etc., also can make people and animals sick. Other illnesses, such as arthritis, diabetes, heart disease related to atherosclerosis, and some kinds of cancer, are not caused by infections. But in some cases, diseases thought to be unrelated to microorganisms have been found to be infectious after all. Stomach ulcers are a good example. Scientists now know that the most common cause of peptic ulcers is infection by a bacterium called Helicobacter pylori.


1. Ask students, Do you think diseases have changed history? Do any diseases affect society today? Tell students that they will be learning about diseases that have had impacts worldwide. 

2. Provide each group with a set of "Disease Information" sheets for a single disease. Each student should receive his or her own copy of the sheet.

3. Instruct each student to read the information on his or her sheet. Depending on students’ reading levels, you may need to provide assistance with the readings. 

4. Have students within each group jointly create a concept map to summarize the important ideas from the group’s “Disease Information: sheet. (At this point, students should be familiar with concept maps.) Then, have each group use its newly-created concept map to prepare a presentation about its assigned disease. 

5. Distribute six copies of the “3-2-1” sheet to each group. 

6.  Have each group present its overview to the class. After each presentation, allow all groups, including the one that just presented, five to six minutes to complete a “3-2-1” sheet on the presentation. Repeat the process until all student groups have made their presentations. 

7. As an assessment, have each group work collectively to create a piece of art that illustrates one of the diseases covered, and then write a paragraph explaining how the artwork represents the chosen disease(s).

8. Ask a student representative from each group to present the group’s artwork in class, along with related information from the readings or other sources. 

9. Allow groups to add information to their concept maps. 

Funded by the following grant(s)

Science Education Partnership Award, NIH

Grant Number: 5R25RR018605