SUMMARY:
* * * Need summary * * *.

Estimated class time:
Two 50-minute class periods. (One for activity and research, one for poster creation and presentation.)

OBJECTIVES:

Students will:

• Distinguish between direct and indirect disease transmission
• Identify various vectors associated with disease
• Simulate the spread of a vector-borne disease
• Research a specific vector-borne disease
• Create and present a poster relating global warming to spread of disease

MATERIALS NEEDED:

• Ball of yarn or string
• Stickers (colored sticky dots will work)
• Index cards (or paper scraps): enough for each student, half with the letter M written on them, half with the letter P.
• Coin
• Internet access
• Poster making supplies (paper, markers, etc.)

PROCEDURES:

Teaching Strategy:

1. Introduce the topic by directing students to "How Diseases Get Spread." As a class, discuss the differences between direct and indirect transmission, and the meaning of the term vector. Tell the class that they will be simulating what might happen in a case of indirect transmission.
2. Have students choose one of the cards having either an 'M' or a 'P' on it. Students that pick up M's will represent mosquitoes and those that get P's will represent people. Tell them not to reveal what roles they are playing.
3. Divide the class into 4 groups and have each group represent a city by standing together in a corner of the room.
4. The ball of yarn represents a bird that is infected with a virus. The teacher calls the name of a student and throws the ball of yarn to that student, while holding on to one end of the yarn.
   1. If the student that catches the ball is a mosquito, then that student chooses another student nearby to tag. If the tagged student is a person, then that student identifies him/herself as being infected by placing a sticker on his/her forehead (or some other conspicuous place). If the tagged student is a mosquito, then nothing happens. Go on to the next turn.
   2. If the student that catches the ball is a person, nothing happens. Go on to next turn.
5. Now the teacher flips the coin. If the toss is heads, the bird stays in that 'city.' If tails comes up, the bird flies to another city or corner of the room. The student who has the yarn, calls the name of another student - either in the same corner or a different corner, depending on the toss of the coin - and throws the ball of yarn to him/her, while holding on to a piece of it.
6. Repeat procedures 4 and 5, ten to fifteen times, being sure that those who catch the ball continue to hold on to a piece of the yarn.
7. At the close of the activity, have students note the tangled web of disease transmission. Discuss the following:
   • How many people got infected with the virus?
   • What were the vectors in this disease?
   • Did the virus stay in one city or did it travel to others?
   • Did the 'people' that came in contact with the 'bird' always get infected? Why or why not?
   • How difficult would it be to trace the path of this disease without the yarn to illustrate it?
   • What was realistic about this simulation?
   • What was not realistic?
8. Now direct students to "Hitching a Ride to Find the Host With the Most," pointing out the three key things that influence the spread of disease. Have students study the case study links about malaria, dengue fever and Hantavirus.
9. Divide the students into groups of 2-3 and assign, or allow them to pick, one of the diseases in the box at the bottom of the page. Add West Nile virus as a choice, even though it's not included on the chart. Students should research their disease choice and then create a poster mimicking the style and types of information contained in the case studies from the site. Be sure to emphasize possible effects that global warming may have on the spread of that disease. Have each group present their poster to the class.

ASSESSMENT:

• Participation in discussion
• Role-playing participation
• Poster and presentation

EXTENSION ACTIVITIES:

• Repeat the activity using different beginning ratios between mosquitoes and people.
• Add a second 'bird' to the activity.
• Research the steps that the CDC takes when tracking the spread of disease.
• Research and present information about recent epidemics in your city or state.

RELEVANT CURRICULUM STANDARDS:

Content Standard F:
As a result of activities in grades 5-8, all students should develop understanding of personal health, risks and benefits, and natural and human-induced hazards:

Students should understand the risks associated with natural hazards with chemical hazards, with biological hazards (pollen, viruses, bacterial, and parasites), social hazards and with personal hazards.

Natural environments may contain substances that are harmful to human beings. Maintaining environmental health involves establishing or monitoring quality standards related to use of soil, water, and air.

Human activities can enhance potential for hazards.

Natural and human-induced hazards present the need for humans to assess potential danger and risk. Many changes in the environment designed by humans bring benefits to society, as well as cause risks.

Health Education Standard 1:
Students will comprehend concepts related to health promotion and disease prevention by describing how lifestyle, pathogens, family history and other risk factors are related to the cause or prevention of disease and other health problems.

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