Propagated Epidemic

 

Purpose:         To simulate a propagated or person to person epidemic and try to identify the                index patient.

 

Materials needed (working alone):

 

            1 tube filled with 5 ml of solution (some tubes with red caps)

            1 ml transfer pipet

            phenol red solution

            1 empty tube

 

Protocol:

 

1. Pickup a numbered tube from the lab instructor.  Record the number on your tube. Pipet 1 ml of your solution into a blood bank (empty tube) and save

 

2. Draw 1 ml of your solution into a pipet and then pick a partner.  Pipet your 1ml of solution into the 4 ml remaining in your patners tube.  Be sure that you each have remove the 1ml to be transferred before the new solution is added.  Mix well.  Record the number of the partner with whom you exchanged fluids.  If your test tube has a red cap choose a second partner and repeat the exchange.  This is the recorded as the first round of the epidemic.

 

3. Repeat step 2 but try to pick a partner from the other side of the lab.  Be careful not to drop your tube or pipet as you move around the lab.  Record the numbers of your partner for the second round of exchange.

 

4. Repeat step 2 and record the number of your partner for the third round of exchange.

 

5. Add 4 drops of phenol red indicator to your tube.  If your tube turns purple you are positive. If you tube remains clear you are negative.  Report your results and the numbers of your partners to the lab instructor.

 

6. The lab instructor will gather the data and help you complete the chart shown below.  Can you identify the index case?  Was there a geographical distribution (ie more infect in the table with the index case)?  Did the red caps have a higher risk of infection?  Finally confirm your results by checking the “blood bank” sample of the suspected index case with phenol red.

 

 

Data:

_________  Number(s) of your partner(s) 1st round,  ___________ second round,  ____________ third round

 

3rd exchange (circle the “infected” individuals and draw arrows to identify their partners)

1   2   3   4   5   6   7   8   9   10   11   12   13  14   15   16   17   18   19   20   21   22    23    24  

 

2nd

1   2   3   4   5   6   7   8   9   10   11   12   13   14   15   16   17   18   19   20   21   22   23    24

 

1st

1    2   3   4   5   6   7   8   9   10   11   12   13  14    15   16   17   18   19  20    21   22   23   24