Module 7 TRANSMISSION OF COMMUNICABLE DISEASES

TRANSMISSION OF COMMUNICABLE DISEASES

Each year, viral diseases such as the cold virus and the flu virus cause disease in humans, and in 2020 we have been affected by a disease called COVID-19, a pneumonia-like disease caused by a novel coronavirus, named SARS-CoV-2, that is similar to the Severe Acute Respiratory Syndrome (SARS) virus. There are also other diseases such as Hepatitis, AIDS, etc that don’t have a respiratory component in disease transmission. These  communicable diseases can  spread from one person to another by contact through coughing, sneezing or sharing body fluids.

This lab activity simulates the spread of disease in a population of people.

You will be using baking soda and the red cabbage pH indicator you prepared in the Lactic Acid Fermentation Experiment.

You will model the spread of an  infectious diseases through “fluid exchange”. One cup will be “contaminated” with baking soda (for a basic pH). Then you will transfer the contents of one water cup to other water cups, in a series. Indication of the pathogen will be visualized by adding the red cabbage indicator and observing the  color differences.

While it is preferable to have another person assist you, if you can’t get an assistant, then you can do this alone.

Materials List:

1. Purple cabbage juice for pH indicator
2. Baking soda
3. Vinegar
4. Eight Clear cups: 8oz size
5. Distilled water

Purple cabbage extract pH indicator

Purple cabbage has a pigment in its dye called anthocyanin which can be used as a pH indicator. It reacts by changing color in acidic and alkaline environments. Chop  1 cup of purple cabbage. Add it to a small saucepan with 1 cup of water Bring to the boil over low heat and simmer for 15 minutes. Strain the liquid into a bowl using a sieve. Allow to cool before using in experiment. The extra can be refrigerated in a jar for further use.

Simulating disease transmission

1. Arrange all eight cups in a row.DO NOT LABEL CUPS.
2. Add 3 oz distilled water to all 8 cups.
3. To ONLY one cup (the first cup in the row, which we will term “Pathogen”), add 1 Tablespoon of baking soda and mix well, till dissolved. From “Cup 1” add 2 Tablespoons of the baking soda solution to the adjacent cup (next cup in the series);let’s call it  “Cup 2”-mix this well and from “Cup 2” add 2 Tablespoons of the now diluted baking soda solution to the third cup in the row/series “Cup three” and mix well. Keep adding 2 tablespoons to the subsequent cup in the row, series in a like manner, till the 8^th
4. Now get help from an assistant, or you yourself rearrange the cups, so that you don’t know which cup held the “pathogen” (the first cup of undiluted baking soda).
5. To each cup add 4oz of the red cabbage juice indicator and determine which cup was “patient 1” or the “index case or patient zero”.
6. Take a photograph of your cups
7. Answer the questions below and submit that along with the image in Blackboard.

Questions:

1. How did you identify patient zero?
2. How many patients had the disease you could identify?
3. If some of your cups had no color change, how would you interpret this result?
4. If a person was “asymptomatic” would that person be able to transmit the disease?
5. What is the difference between aerosol and droplet transmission? (you may need to use a resource outside the textbook to answer this).
6. What is the hazard an asymptomatic carrier poses?
7. How do face masks help in preventing the transmission of droplet or aerosols?
8. With the COVID-19 pandemic, we hear the terms “mitigate” and “flatten the curve”. What do these phrases mean?
9. R₀, or “R naught,is another term used.What is this?
10. What other methods of disease prevention can you implement, to ?
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