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Overview of Germs and Infectious Agents
Summary: This lesson is meant to engage high school students using a demonstration to show
how germs and other infectious agents are transmitted using the Glo Germ solution. After this
experiment and presentation, students will be able to distinguish among the types of infectious
agents that exist, as well as learn about effective preventative measures that can reduce the risk
of exposure and transmission of infectious agents. This lesson plan can be in used in a biology
course.
Learning Outcomes:
 Students will be able to define what an infectious disease is, as well as identify the major
classes of infectious agents.
 Students will identify the two types of disease transmission (direct vs. indirect), as well as
identify examples of each type.
 Students will understand the appropriate preventative measures to protect themselves
from infectious agents, including the proper technique for hand hygiene.
Materials:
 One Glo Germ bottle (2 ounce liquid bottle will last several years).
 One UV light.
 One bottle of antibacterial soap.
 A clean, functional sink to provide running water.
 Computer and projector for PowerPoint presentations.
Total Duration: ~ 60 minutes.
Procedure
Teacher Preparation
A few minutes before class, place a small amount of Glo Germ on the outside door handle of the
classroom and on select students’ desks. Prepare a PowerPoint presentation (or use the
presentation provided) to guide the instruction. Make copies of proper hand hygiene procedures
from the CDC website to provide the students.
Title: Glo Germ
URL: http://www.glogerm.com
Description: This site sells Glo Germ products (the solution and UV light) to help
demonstrate the importance of proper hand washing.
Title: CDC – One Ounce of Prevention Campaign
URL: http://www.cdc.gov/ounceofprevention/
Description: This CDC website gives information on the Ounce of Prevention
Campaign, promoting good hygiene. Instructors can download free hygiene posters and
resources.
Introduction: A few minutes before class, place a small amount of Glo Germ on the outside
door handle into the classroom and on select students’ desks. As the students enter the
classroom, they will transfer the Glo Germ to their hands, other classmates, and various surfaces.
When the students are settled, explain that there has been an announcement from the local health
department that an outbreak of an unknown germ. It is unknown if the pathogen is dangerous,
but it can be detected by a UV light. Under UV light, the pathogen will appear as orange streaks
or spots.
Step 1: Turn out the lights in the classroom and ask students to cup their hands under the UV
light to test for the unknown germ. As the teacher moves from student to student, the students
can be separated into who tested positive and who tested negative for the germ (10:00).
Step 2: Lead a discussion using the PowerPoint slides (“Understanding Epidemiology: Infectious
Agents and Preventative Measures”) to determine students’ knowledge regarding the following
questions (20:00)
 What are infectious agents? Are there different types?
 Where infectious agents are commonly found?
 How are germs transmitted?
 What ways can one reduce exposure to germs and infectious agents?
Step 3: Once the discussion is complete, have student who tested positive wash their hands and
be re-tested under the UV light for presence of the germ (10:00).
Step 4: Lead a discussion using the PowerPoint slides (“Understanding Epidemiology: Infectious
Agents and Preventative Measures”) to explain the importance of properly washing one’s hands,
and discuss why it is important to human health and public safety (15:00).
Title: CDC – Handwashing Guidelines
URL: http://www.cdc.gov/nceh/vsp/cruiselines/handwashing_guidelines.htm
Description: This CDC website with guidelines for proper hand washing.
Modifications
For a longer presentation, students who tested positive for the unknown germ can then work in
teams with other students to plate the germ onto Agar plates. Further instructions for this
procedure, can be found at:
Title: It’s a Germy World After All
URL: http://www.cdc.gov/excite/ScienceAmbassador/ambassador_pgm/lessonplans/
Germy-World.pdf
Description: Teaching resource for high school students and activities in the classroom.
Homework assignment: Have the students complete the following worksheet about infectious
agents. Ask them to divide into 7 teams and present material on each of the five types of
infectious agents.
1) Define each of the follow types of biological agents that can cause infectious diseases:
Metazoa =
Bacteria =
Virus =
Fungi =
Protozoa =
Rickettsia =
Prions =
2) Indicate which type of infectious agent causes the each disease listed below:
Salmonella ____________________________
Giardiasis _____________________________
Bovine spongiform encephalopathy ______________________________
Rocky Mountain Spotted Fever _________________________________
Influenza ______________________________
Candidiasis _____________________________
Creutzfeldt-Jakob Disease ____________________________
Methicillin resistance Staphylococcus aureus (MRSA) _________________________
Malaria ___________________________
Typhus ___________________________
Measles ___________________________
Teacher’s Answer Guide:
1) Define each of the follow types of biological agents that can cause infectious diseases:
Metazoa = most simple, multi-cellular animals; many of which are parasites.
Bacteria = single-celled organisms that lack a nucleus, and are responsible for a wide
range of human diseases.
Virus = very small, consisting of an RNA or DNA core, and an outer coat of protein.
They can reproduce and grow only inside of living cells.
Fungi = non-motile, filamentous organisms that cause disease that can be very difficult to
treat.
Protozoa = single-celled organisms with a well-defined nucleus; some of these are
human parasites.
Rickettsia = a genus of bacteria usually found in the cells of lice, ticks, fleas, or mites.
They are smaller than most bacteria and share some characteristics of viruses.
Prions = infectious agents that do not have any genes. They appear to consist of a
protein with an aberrant structure, which replicate in animal and human tissue. These
biological agents cause severe damage to the brain.
2) Indicate which type of infectious agent causes the each disease listed below:
Salmonella: Bacteria
Giardiasis: Protozoa; infection of the upper small intestine that causes a diarrheal illness.
Bovine spongiform encephalopathy: Prion; disease seen in cows; also known as “mad
cow disease.”
Rocky Mountain Spotted Fever: Rickettsia; tick-borne systemic disease that can be
difficult to diagnose.
Influenza: Virus; respiratory illness that contributes to development of pneumonia.
Candidiasis: Fungi; causes lesions on the skin or mucous membranes, including “thrush.”
Creutzfeldt-Jakob Disease: Prion; disease seen in humans.
Methicillin resistance Staphylococcus aureus (MRSA): Bacteria; can affect almost every
organ system with illness ranging from mild to severe, and even causing death.
Malaria: Protozoa; mosquito-borne disease that is one of the top three infectious diseases
in the world.
Typhus: Rickettsia; louse-borne rash illness with a high fatality rate that has occurred
historically in poor living conditions.
Measles: Virus