Materials Included In Kit

Additional Materials Required

Prelab Preparation

1. Place the pump onto the bottle of hand lotion and prime the pump.
2. Place the gloves and hand lotion in a central location for students to use.
3. Assign each student to a city and identify each as a “Traveler,” “Friend” or “Spokesperson” prior to start of the class (see the Lab Hints).
4. Pump one aliquot of Glowing Germ onto a pair of gloves and rub it into the gloves. Remove the gloves and set them to the side.
5. As students are beginning the activity, put the glowing germ pair of gloves on your hands and demonstrate how students will be shaking hands. This way the teacher becomes the vector for contamination.
6. Shake the hand of only one student who will be traveling to the airport.

Safety Precautions

The glowing germ is hand lotion with a nontoxic UV-sensitive dye. It is harmless but should be treated as a laboratory chemical. Remind students to wash their hands thoroughly with soap and water before leaving the laboratory. Please consult current Safety Data Sheets for additional safety, handling and disposal information.

Disposal

Please consult your current Flinn Scientific Catalog/Reference Manual for general guidelines and specific procedures, and review all federal, state and local regulations that may apply, before proceeding. Gloves, glowing germ, hand lotion and index cards may be disposed of according to Flinn Biological Waste Disposal Type VI, in the regular trash.

Lab Hints

• Enough materials are provided in this kit for five classes of 30 students. This laboratory activity can reasonably be completed in one 50-minute class period.
• The number of exchanges each participant conducts and the number of gloves initially “infected” will determine the ultimate rate of “infection.” For class size of 30 or less, one carrier should provide a dramatic result. The instructor should direct a minimum of three exchanges per participant for smaller classes but no more than six for up to 35 participants.
• Two travelers from each city works well for a class of 30 students. One spokesperson per city.
• Note: The glowing germ material will spread around the classroom. Make sure students only touch another gloved hand or the index cards with the contaminated gloves.
• Borrow and hang posters for each city. For example, New York, Paris, Moscow and Tokyo would demonstrate global travel.
• Name the airport by choosing a very busy international airport, such as London’s Heathrow Airport, Atlanta’s Hartsfield-Jackson International Airport, Chicago’s O’Hare International Airport or Tokyo’s Haneda Airport.
• Create and laminate tickets or passports for the students with the city name, a landmark and their assigned role of “traveler,” “friend” or “spokesperson.” Hand these out to students at the beginning of the activity.
• Do not allow students to “high five” as the lotion will splatter.

Teacher Tips

• This activity is an exciting alternative to the typical infectious disease activity, such as that of phenolphthalein and a base.
• Repeat the activity, but have one or two students replace their gloves (equivalent to washing their hands) after they shake hands with someone else. Compare the outcome of the two scenarios.
• Advanced classes may benefit by substituting Serratia marcescens for the Glowing Germ lotion. A sample of S. marcescens in a liquid culture may be swabbed onto one student’s gloves while the other students swab sterile saline solution onto their gloves. After shaking the hands of three students, students then use a sterile swab to culture their gloves. S. marcescens will grow on the plates of infected students. Use aseptic technique and all appropriate microbiology safety procedures when handling S. marcescens. Agar, Petri dishes, sterile swabs and S. marcescens are all available from Flinn Scientific, Inc. Sterile saline solution is available at many discount stores.

Further Extensions

To further explore disease transmission, see Flinn Catalog No. AB1210, AIDS—Transfer of Body Fluids Kit.

Answers to Prelab Questions

1. In your opinion, why do some people get sick while others remain healthy?

   Answers may include personal hygiene, individual health, genetics and other reasonable explanations.

2. List three personal protection strategies.

   Answers may include personal hygiene issues such as washing hands frequently, bathing, wearing masks when around infectious individuals, vaccinations, disinfecting formites, not sharing formites and isolation.

3. List two strategies that society uses to control and contain a contagion.

   Answers may include vaccinations, isolation, antibiotics, hand washing facilities, disinfectants and sick leave.

4. A person becomes infected and is contagious for one day after becoming infected. If that person comes in contact ten people the first day and 50% become infected and the newly infected people also contact the second day (their contagious day) ten people each with a 50% infection rate, how many people are newly infected after three days? Five days? Seven days?
   {10760_PreLabAnswers_Figure_1}

Sample Data

Citizen Overhead

*Infected † Initially infected

Citizen Exchange Overhead

Answers to Questions

1. Using the class data, determine the person who initially began the epidemic.

   After the students eliminate the classmates who did not pass on the glowing germ they should be able to narrow the initial infection to the student who modeled the hand shake with the instructor.

2. How would the results differ if more students were initially infected?

   The number of infected students would have increased.

3. How would the results differ if people were drove directly to another city instead of having to travel through the central airport?

   There would have been a trail of infection along the route instead of pockets of infection. The number of infected people may increase or decrease due to changes in contact.

4. How would the results differ if the infectious person showed visible symptoms?

   Human nature causes people to avoid obviously infected individuals and the airline industry may ban an obviously ill person from flying.

5. Suggest several ways the illness in this activity could have been controlled to prevent its spread.

   Answers may include surveillance and control techniques, isolation, personal hygiene measures and disinfection of formites.

6. If a person who is infected with an incurable virus contacts four other people and 75% of those contacted become ill, how many generations of contact will it take for more than 3000 people to become infected?

   Six.

   1. Graph the infection generation versus the number of new infections.
      {10760_PreLabAnswers_Table_1}
      {10760_PreLabAnswers_Figure_2}

Teacher Handouts

10760_Teacher1.pdf

Introduction

A World Health Organization (WHO) report shows that one-third of all deaths worldwide are due to infectious and parasitic diseases. Infectious and parasitic diseases are spread from person to person mainly through air, water and physical contact by way of small organisms called pathogens. Most pathogens are difficult to avoid as they cannot be seen. Examples of pathogens are viruses, bacteria, fungi and infectious parasites, such as Plasmodium, amoeba and nematodes. The Epidemic simulates the transmission of a pathogen through physical contact. Many pathogens are transmitted in this manner.

Concepts

• Disease control
• Epidemiology
• Infectious disease
• Disease prevention
• Formites
• Pathogen

Background

The terms contagion, causal agent and pathogen are broad terms used to describe any virus, bacteria, prion (protein), protozoa, worm or genetic mutation that causes harm to living things. Most of these potential disease agents are invisible to the naked eye and also fairly widespread—the majority of surfaces are covered with beneficial and pathogenic microbes. It is the type and concentration of pathogenic microbes, combined with the health and immune capabilities of the human host that determine how, when and if a person will get sick. The study of how and why people and animals become ill and how to prevent and control illness is called epidemiology.

Epidemiologists define an infectious disease as any disease easily transmitted by contact between a host and a victim. Contact can be direct, between two individuals through kissing, hugging or shaking hands. Contact can also be indirect. In this case the contagion is transmitted by contact with an inanimate object that harbors the pathogen. These inanimate objects are called formites. Toys, money, kitchen sponges, cups, toothbrushes and pencils are just a few examples of formites. Formites become infected by touch, through droplets created by coughing, sneezing, talking or through airborne particles that float in the air for a long time and eventually settle on the surface of various objects. Formites can be contagious for minutes or days, depending on the contagion. Disinfecting formites frequently, avoiding the sharing of formites, cleaning hands after touching a formite and staying away from other people when they are (or you are) contagious are the best methods of controlling mild illnesses.

Epidemiologists are the disease detectives of the world. They use scientific methods to determine why some people get sick and others do not, how and why people are sick and also how to control the spread of an illness. Epidemiologists have identified six causes of disease emergence in the world. These causes are:

1. Evolutionary changes in the DNA or RNA of the pathogen leading to drug resistance or an increased ability to infect.
2. Pathogens invading new geographic area and new populations through world travel and global commerce.
3. Environmental changes that lead to new exposures such as climate changes, deforestation, conversion of grazing areas to growing areas and the creation of wet areas in which mosquitoes can breed.
4. Consolidation of people into urban areas leading to more contact between infected and non-infected people and more pollution.
5. Discovery of previously unrecognized pathogens.
6. Slow government response to new problems and misdiagnoses by physicians.

The focus of this activity will be on causes 2 and 4 from the list, the globalization of the world through travel and the consolidation of people into small areas leading to the spread of infectious diseases worldwide.

People may be contagious before they exhibit any external symptoms of illness while they exhibit symptoms for most pathogens and, for some pathogens, even after they appear well. In an urban setting, an infected or contagious individual may encounter hundreds of potential victims a day. This aspect of urban life generates an exponential infection rate. For example, one contagious person who has direct contact with just four people may pass the illness onto 75% of them. The next infection generation begins with four infected individuals, the original and three victims. These four individuals would contact an additional 16 individuals, 12 of whom would become infected and so on.

Vaccination is an effective means of preventing people from getting sick when they are exposed to the same contagion contained in the vaccine. Epidemiologists routinely investigate if the people in close contact with an infectious person have been vaccinated against that particular contagion. Any non-immune person is vaccinated. This is called ring vaccination or surveillance and containment. Surveillance and containment manages an outbreak of disease by means of vaccination or prescribing antibiotics to the people in immediate contact with the sick individual and then monitoring those individuals for symptoms of the illness. The idea is to form a “buffer” of immune individuals to slow down the rate of infection and thus prevent the disease from spreading to the general population.

Experiment Overview

This activity simulates the spread of an infectious disease throughout the globe. The participants will represent the populations of four large cities. Interaction among the separate cities will occur as several individuals from each city travel through a central international airport. At the completion of this simulation, students will understand how pathogens can quickly infect the entire world population, why some people remain unaffected after exposure and how the identity of the originally infected person can be found by analyzing data collected during the simulation.

Materials

Prelab Questions

1. In your opinion, why do some people get sick while others remain healthy?
2. List three personal protection strategies.
3. List two strategies that society uses to control and contain a contagion.
4. A person becomes infected and is contagious for one day after becoming infected. If that person comes in contact ten people the first day and 50% become infected and the newly infected people also contact ten people the second day (their contagious day) each with a 50% infection rate, how many people are newly infected after three days? Five days? Seven days?

Safety Precautions

Although the materials used in this laboratory are considered nonhazardous. May cause irritation to individuals with extremely sensitive skin. Please follow appropriate laboratory safety procedures. Wash hands thoroughly with soap and water before leaving the laboratory.

Procedure

1. Move desks to the perimeter of the classroom.
2. Receive a travel assignment from the instructor.
   1. Move to your assigned home city.
   2. All “Friends” write their name on two index cards and label the cards 4 and 5.
   3. All “Travelers” write their name on five index cards and label them 1 through 5.
3. Put on the disposable gloves.
4. Put hand lotion onto the gloves and rub it in. Note: Do not touch anything but the index cards and the gloved hands of other students. Shake hands only as demonstrated by the instructor.
5. All “Travelers” take their index cards and proceed to the central airport located in the center of the room.
6. Each “Traveler” shakes the hand of another traveler and they exchange index card 1 with one another.
7. Each “Traveler” shakes the hand of a second (different) traveler and they exchange index card 2 with one another.
8. All “Travelers” return to their home cities.
9. Each “Traveler” shakes the hand of one “friend” from the same city and they exchange index card 3 with one another. Note: The “friend” will give index card 4 to the “traveler.”
10. Each “Traveler” shakes the hand of a second “friend” and they exchange index card 4 with one another.
11. Each “Traveler” shakes the hand of a third “friend” and they exchange index card 5 with one another.
12. Each “friend” with an unexchanged card shakes the hand of another “unexchanged” friend.
13. Do not touch anything else with the gloves—wait for the instructor to use a black light and check your gloves for contamination.
14. As the instructor finishes analyzing the gloves, turn the gloves inside out as they are removed to trap the contamination inside the gloves. Dispose of the gloves as directed by the instructor.
15. On the Citizen Overhead write your name in the citizen column in red if you were infected, in black if you were not infected.
16. Return to your home city.
    1. Write your name on each of the index cards you acquired during the activity.
    2. Mark each index card as either infected or healthy as the names are recorded in red or black on the Citizen Exchange Overhead.
    3. Once each of your cards is complete, give the cards to the city’s “Spokesperson.”
17. The “Spokesperson” will transcribe the information from the cards onto the Citizen Exchange Overhead. Once again, infected citizens are to be written in red and healthy citizens in black. The remaining citizens should begin to answer the Analysis and Conclusions Questions.
18. Consult your instructor for appropriate disposal procedures.

Analysis and Conclusions

1. Using the class data, determine the person who initially began the epidemic. Hint: Eliminate all infected citizens that exchanged with a citizen who did not then become infected—these infected individuals cannot be the original carriers.
2. How would the results have been different if more students had been initially infected?
3. How would the results have been different if people had driven directly to another city instead of traveling through the central airport?
4. How would the results have been different if the infectious person had shown visible symptoms?
5. Suggest several ways the illness in this activity could have been controlled to prevent its spread.
6. If a person who is infected with an incurable virus contacts four other people and 75% of those contacted become ill, how many generations of contact will it take for more than 3,000 new people to become infected? Graph the infection generation versus the number of new infections.