Buzz…Buzz…Bite!

Part 1: Direct Transmission—Human to Human

Direct human-to-human disease transmission occurs between an infected person and an uninfected person. Examples of diseases spread through direct transmission between humans include the common cold (rhinovirus), flu (influenza) and AIDS (acquired immune deficiency syndrome). Direct transmission can result from direct contact (touching, bodily fluids) or indirect contact (touching an infected surface).

Instructions: Each cup of liquid represents the bodily fluids of a human. Someone in the class will receive fluids “infected” with a disease. You do not know who is “infected” and who is not, but this investigation will allow you to use your detective skills to figure out who introduced the disease into the population. That person is the index patient, sometimes called “Patient Zero.”

Materials (for each student): Hints: Only exchange once per round. One disposable cup with unknown liquid Do not exchange with the same person twice. One disposable plastic pipet Both partners exchange during each round.

Procedure (this game will remind you of Musical Chairs!):

Caution: Some of the liquids are poisonous to taste or touch. Do not drink any fluids in this lab. If a liquid spills on your skin, wash it off immediately with plenty of cold water.

Choose a cup and pipet. Record the cup number in the Data Table. Students with odd-numbered cups form a circle in the middle of the room. Students with even-numbered cups walk around the outside of the circle.

Round 1: When instructed, students in the outer circle will begin to walk around the inner circle. When the

teacher gives the signal, stand in front of someone sitting in the inner circle. When instructed, squirt two pipets full of fluid from your cup into the cup of the person in front

of you. Your partner will do the same. Record your partner’s cup number in the Data Table. Then wait for everyone in the class to

finish. Round 2:

When instructed, the outer circle will walk around the inner circle again and each student will find a new partner.

Repeat the fluid exchanges just as in Round 1. Do not exchange with the same person twice. Record your new partner’s cup number. Wait for everyone to finish.

Round 3: Repeat this procedure one more time and then return to your seat. Your teacher will add an indicator solution to each cup. “Infected” students will see a color

change.

Peabody Explorers and Investigators. © 2013 Yale Peabody Museum of Natural History. All rights reserved.

Conclusion: Make a chart to track disease transmission. Can you figure out who was originally infected?

DATA TABLE: Did any errors occur in this lab? If so, how do youthink these errors will affect the results?

Your Cup #_____ Round 1 Cup #_____

Round 2 Cup #_____

Round 3 Cup #_____

Who was originally infected? Cup # _____

DATA CHART

Cup # Round 1 Cup #

Round 2 Cup #

Round 3 Cup #

Results (+/–)

123456789

101112131415161718192021222324

Buzz…Buzz…Bite!

Peabody Explorers and Investigators. © 2013 Yale Peabody Museum of Natural History. All rights reserved.

Part 2: Indirect Transmission—Human to Vector to Human

The second part of this activity simulates indirect vector-borne disease transmission. Transmission is indirect when humans transmit the disease to other humans, but not directly person-to-person. A vector, such as a mosquito or sand fly, picks up the pathogen (disease-causing organism) from an infected human and passes it to an uninfected human. One person transmits the disease to another person, even though there is no direct contact. Examples of vector-borne diseases include dengue fever, malaria, and leishmaniasis.

Instructions: Students are either Humans or Sand Flies. Divide the class in half randomly by cup selection. Each cup of liquid represents the bodily fluids of either a human or a sand fly. Someone in the class will receive fluids “infected” with a disease. You do not know who is “infected” and who is not.

Note: Only Humans will be initially “infected” in this activity, in order to demonstrate how infected humans can transmit pathogens indirectly to uninfected humans through a sand fly vector. Materials: Hints: Only exchange once per round.

One disposable cup with unknown liquid Do not exchange with the same person twice. One disposable plastic pipet (for Sand Flies only!) Only Sand Flies have pipets to exchange.

Procedure (just like Part 1, this game will remind you of Musical Chairs!):

Caution: Some of the liquids are poisonous to taste or touch. Do not drink any fluids in this lab. If a liquid spills on your skin, wash it off immediately with plenty of cold water.

Everyone chooses a cup, but only Sand Flies take a pipet. Record your cup number in the Data Table. Humans form a circle in the middle of the room. Sand Flies walk around the outside of the circle.

Round 1: When instructed, students in the outer circle will begin to walk around the inner circle. When the

teacher gives the signal, stand in front of someone sitting in the inner circle. When instructed, Sand Flies squirt two pipets full of fluid from your cup into the cup of the

Human in front of you. (A sand fly can transmit protozoa in its saliva when it bites a human.) Sand Flies then take two pipets full of fluid from the Human’s cup. (When taking blood, a sand fly can consume protozoa in the human’s blood.)

Record your partner’s cup number in the Data Table. Then wait for everyone in the class to finish.

Round 2: When instructed, the outer circle will walk around the inner circle again and each student will

find a new partner. Repeat the fluid exchanges just as you did in Round 1. Do not exchange with the same person

twice. Record your new partner’s cup number. Wait for everyone to finish.

Round 3:

Peabody Explorers and Investigators. © 2013 Yale Peabody Museum of Natural History. All rights reserved.

Repeat this procedure one more time and then return to your seat. Your teacher will add an indicator solution to each cup. “Infected” students will see a color

change.

Peabody Explorers and Investigators. © 2013 Yale Peabody Museum of Natural History. All rights reserved.

Conclusion: Make a chart to track disease transmission. Can you figure out who was originally infected?

DATA TABLE: Did any errors occur in this lab? If so, how do youthink these errors will affect the results?

Your Cup #_____

Round 1 Cup #_____

Round 2 Cup #_____

Round 3 Cup #_____

Who was originally infected? Cup # _____

RESULTS CHART

Cup # Round 1 Cup #

Round 2 Cup #

Round 3 Cup #

Results (+/–)

Sand Fly 1Sand Fly 2Sand Fly 3Sand Fly 4Sand Fly 5Sand Fly 6Sand Fly 7Sand Fly 8Sand Fly 9

Sand Fly 10Sand Fly 11Sand Fly 12

Human 1Human 2Human 3Human 4Human 5Human 6Human 7Human 8Human 9

Human 10Human 11Human 12

Peabody Explorers and Investigators. © 2013 Yale Peabody Museum of Natural History. All rights reserved.

Buzz Buzz Bite Teacher Notes

Part I is a classic direct disease transmission lab often used to demonstrate HIV or influenza transmission from person-to-person contact.

Part II is an adaptation of this lab to simulate indirect transmission of vector-borne diseases. This section demonstrates transmission by sand flies of the Leishmania donovoni protozoan that causes cutaneous leishmaniasis in humans.

Reagents: Measurements do not need to be exact.

Infected Solution: Sodium carbonate (washing soda) 1 g = approx. ¼ teaspoon100 mL water

Indicator Solution: Phenolphthalein: 0.1 g = approx. ¼ of 1/8 teaspoon100 mL ethyl or 70% isopropyl (rubbing) alcohol

Phenolphthalein indicator will turn dark pink or red in the presence of a base (washing soda).

Non-toxic Reagents: Measurements do not need to be exact.

Infected Solution: 2 tbsp. baking soda500 ml of water

Indicator Solution: 1/4 tsp. turmeric4 tbsp. isopropyl (rubbing) alcohol

Turmeric indicator solution will turn orange or red in the presence of a base (baking soda).

Procedures: Part I (Direct Transmission):

This activity requires an even number of students. Number the cups sequentially: 1, 2, 3, etc. Each student takes a cup of fluid and a pipet. Approximately 10% of the class should receive “infected” solution and the rest of the cups will

contain water. Fill all cups with the same volume of fluid and record the cup numbers of those “infected.” Be careful to avoid cross-contamination.

The following materials may help you keep track of the exchanges:o Chart or paper posted on the board for students or teacher to fill in data after each

exchange. o Sticky notes attached to each cup to record exchanges.

Use logic to determine the transmission pathway and identity of the initial infected patient.

Peabody Explorers and Investigators. © 2013 Yale Peabody Museum of Natural History. All rights reserved.

Part II (Indirect Transmission):

This activity requires an even number of students. Half are Sand Flies and half are Humans. Assign roles to students or allow them to select for themselves.

Number cups sequentially: S1, S2, S3, etc., for Sand Flies; and H1, H2, etc., for Humans. Each student takes a cup of fluid, but only Sand Flies take a pipet. All Sand Flies are females that

must feed on blood to develop their eggs. The pipet represents the sand fly proboscis (mouthpart) to bite and take a blood meal.

Only Humans will be initially “infected” in this activity, in order to demonstrate how infected humans can transmit pathogens indirectly to uninfected humans through a sand fly vector. Approximately 10% of the Humans should receive “infected” solution and the rest of the cups will contain water. Fill all cups with the same volume of fluid and record the cup numbers of those “infected.” Be careful to avoid cross-contamination.

The following materials may help you keep track of the exchanges:o Chart or paper posted on the board for students or teacher to fill in data after each

exchange. o Sticky notes attached to each cup to record exchanges.

Use logic to determine the transmission pathway and identity of the initial infected patient.

Peabody Explorers and Investigators. © 2013 Yale Peabody Museum of Natural History. All rights reserved.