West Nile Virus

Now we will go outside and do an activity to model mosquitoes and birds.

West Nile Virus Game

Purpose: Give students sense of what affects spread of diseases.

Materials:

• Tally sheets (attached).
• Post-it of two colors (one for birds and one for mosquitoes).
• Tokens (I am thinking strips of paper, with 2 strings of several symbols, most of symbols being random, but one designating whether the person carrying the strip is currently infected or might have become infected. This way students can't tell whether they are infected or not. It would be good to have different colored tokens for birds and mosquitoes.)
• Some kind of timer.
• Some way to mark the boundaries of the "swamp" where the activity takes place.

General Instructions:

Do the activity twice. The second time, decrease the size of the "swamp" to make it harder for the birds to avoid the mosquitoes and use the faster-spreading parameters in the instructions for monitors. On the second round, you can switch roles, so the mosquitoes become birds and vice versa (it feels fairer, but the groups need to pretty balanced).

If you are feeling deceptive, you can say that you are keeping track of the tokens so you can find out which mosquito got the most blood (rolling the dice to find out how much the mosquito got) and which bird lost the least blood. The mosquito who gets the most blood wins (which pretty much is what happens in reality, because more blood means more eggs, which means more descendents). Also the bird who loses the least blood wins (which also realistic).

Instructions for students: Half of the students get mosquito-designating post-its, half get bird-designating post-its. The mosquitoes need to chase the birds. A mosquitos "genetic success" depends on biting lots of birds (so the winning mosquito bites the most birds, we don't want mosquitoes sitting around being worried about becoming infected in fact, neither species bases its behavior on the possibility of infection). A birds success depends on not getting bit, so they try to avoid mosquitoes. Birds and mosquitoes chase one another through the "swamp." When a mosquito bites a bird, they each tear their token in half, keeping one half and giving the other to the other one. They then need to go check in with the monitors. In checking in with monitor, they show the two pieces of token to the monitor, roll dice, and then get given a new token and go back to "the swamp."

Instructions for monitors: In issuing the tokens, give 1 of the mosquitoes a token for being infected (say with a * in the third character). Try to choose the infected mosquito to have at least an average level of success at catching birds (if in doubt, use 2 infected mosquitoes). Give everyone else an uninfected token.

When students check in after a "successful bite," they need to roll dice. They then get a new token based on the following table:

	Own Token	Other Token	Roll Round1	Roll Round2	Result Has
	*		Has *		1-6		1-6		Already infected, give token with * Has
	*		No *		1-6		1-6		Already infected, give token with * No
	*		Has *		1-2		1-4		Becomes infected, give token with * No
	*		Has *		3-6		5-6		Bitten by infected but does not become infected, give a token without * No 
	*		No *		1-6		1-6		Is not infected, give token without *

Monitors write the number rolled and the initials of the player on the taken and hand both parts to the recorder.

Note that in the second round, the birds will have a harder time avoiding the mosquitoes and the disease is more infectious, so the disease should spread faster.

Instructions for Recorders: Have separate bird and mosquito recorders? When you get a pair token-halves from the monitor, record a tally in the correct cell: Time */* */No No*/*/inf No*/*/not No*/No* Minute 1 Minute 2 Minute 3

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