Rabbit island case study answers

Case Study 1

A Simple Plan: E.L. Trudeau, the Rabbit Island Experiment, and Tuberculosis Treatment

Part I The Rabbit Island Experiment

1. The data from the experiment Dr. Trudeau describes is shown below in Figure 1. Graphs like Figure 1 are called survival curves. Describe Figure 1 in your own words. Explain why the rabbits are emaciated in groups 1 and 2.

2. Develop an answer to each of Dr. Trudeau’s questions:

What results ensue when both bacillary infection and unhygienic surroundings are made to coexist in tuberculosis?

Are unhygienic surroundings when every known precaution has been taken to exclude the bacillus sufficient of themselves to bring about the disease?

Is bacillary infection invariably progressive in animals placed under the best conditions of environment attainable?

3. Do Dr. Trudeau’s results support the germ theory of infection? Why or why not?

4. What do the data suggest might be good environmental conditions for tuberculosis patients?

5. What might be the effect of crowding on effective exposure rate of individual animals to MTb? (Hint: Would you rather board an airplane for a 3-hour trip where 2 out of 300 passengers had the flu or board an airplane where 200 out of 300 passengers had the flu?)

6. What is the dependent variable in the Rabbit Island Experiment? Also, list all of the independent variables you can think of in the experiment.

7. Select any one of the independent variables you have listed above and design an experiment similar to Dr. Trudeau’s. State your experimental question, i.e., what are you trying to find out. Formulate a hypothesis. Then decide upon and write out a description of how you will manipulate your treatment groups.

8. We respect Dr. Trudeau and all those earlier scientists who did the best they could within the contemporary understanding of the problem they addressed and utilizing the materials and technology they had at hand. Modern-day biologists like to talk about resistance/susceptibility genes and patterns of inheritance, rather than family blood. They think about infectious disease in terms of microbes and pathogenicity, rather than speaking of bad humors. They have identified vitamins and other nutrients that are abundant in some foodstuff s and lacking in other that are essential for optimal immune function. Without the benefit of such modern formulations, Dr. Trudeau, by a disciplined application of scientific curiosity and careful, clever methodology, shed light on each of these concerns, light that helped to illuminate the minds of scientists who came after. Still, a look at his original paper leaves us wondering, were the rabbits genetically identical? Probably not! Why? Were they all of the same sex and age? Couldn’t he have given the animals kept on short rations just a smaller amount of the same varieties of food available to the animals fed abundantly—after all, there might be some important nutrient missing in potatoes. In light of the title of the paper, why not measure bacterial numbers in the rabbits on post mortem rather than just survival time? (In a subsequent paper, he did exactly that.) Once you start critiquing an experiment from 100 years ago, or 10 years ago, or sometimes even last year, it’s hard to stop. Can you think of anything else you would have changed about the Rabbit Island Experiment?

9. Suppose you were the Mayor of New York City in the 1890s/early 1900s and were convinced by Dr. Trudeau’s experiments that in your city a transmissible bacterium was causing tuberculosis and that poor living conditions and inadequate diet were adversely affecting the ability of hundreds of people to fight the infection. What sort of public policies might you try to enact in order to combat the public health menace? What obstacles might you encounter?

Part II – Tuberculosis in Social Context

1. The curve shown in Figure 2 has three parts, from 1700–1800, 1800 to approx. 1955, and 1955 to approximately 1985. The data used to produce the curve are from Western Europe, but a similar one could be expected for the United States. Write a sentence telling why each part of the curve looks the way it does. In looking just at this graph, what would you predict about the death rate from TB in 2000 and 2005?

2. Tuberculosis causes nearly 2 million deaths worldwide each year. Between 1985 and 1992, cases of TB in the United States increased by 20 percent, as shown in Figure 3. Write a paragraph suggesting a few reasons why this resurgence of TB might have occurred in the United States

3. The resurgence lasted until approximately 1992, then, in the United States, it began to abate. In 2005 the TB case rate in the U.S. was 4.8 per 100,000, as the U.S. medical community brought the epidemic under control (Centers for Disease Control & Prevention, National Prevention Information Network, n.d.). However, in U.S. prisons and all over the world TB remains a serious health problem. In the U.S., zero tolerance drug laws have resulted in a burgeoning incarcerated population, which constitutes a significant reservoir of disease, with a far higher incidence rate than the general population. In New York prisons, the incidence rate of TB is 156.0/100,000compared to the rate of 10.4/100,000 in the general population (U.S. Agency for International Development, 2009). Considering all you have learned in Parts I and II, discuss why these rates may be so much higher in prison.

4. All of the following factors are important in causing the worldwide resurgence of tuberculosis: (a) emergence of strains that are resistant to one or more of the available antibiotics effective against MTb; (b) incomplete or inadequate understanding by scientists of the details of the host/pathogen interaction in MTb infection; (c) lack of a universally-accepted vaccine; (d) lack of financial support for science and for public health initiatives in developing countries; (e) famine; (f) geopolitical instability in the developing world; and (g) inadequate public awareness of public health issues. If you were a billionaire philanthropist like Warren Buffet or Bill Gates, where would you focus your efforts against tuberculosis?