Bobbi Swain and John Nishan
Woodrow Wilson Biology Institute
In this exercise you will test your
problem-solving skills, your ability to see connections, and your
ability to draw conclusions and inferences from information provided
in this case study. The case involves some of these ideas:
Joy Rhodes and her husband, Fred,
are pharmacologists and epidemiologists and have been "prospecting"
(searching) for and developing drugs for many years. Although
their previous work had been in Africa, they have decided to make
a trip to the Amazon rain forest at the suggestion of Barbara
Morgan, an anthropologist whose parents worked as missionaries
in the area for 25 years. Barbara has found a village of people
called the Iboti, who have had little or no contact with the modern
On the visit in 1985, Joy and Fred
communicate with the Iboti using Barbara to translate the language.
In the village, many of the people are ill with a disease they
call akalua hisbanani, roughly translated to mean "that
which weakens the body and drains it of fluids" or "wasting
sickness." The disease is not new to the Iboti. Chills,
fever, diarrhea, vomiting, fatigue, and a rash across the abdomen
are the symptoms. For many years, it has been successfully treated
with a tea made by boiling the leaves of the noa tree. Joy and
Fred decide to take blood samples to investigate the cause of
the disease since symptoms indicate that it is probably viral
or bacterial in origin. They take leaf samples from the noa tree
as well as many other specimens identified by the natives as having
medicinal applications. They carefully record the names of the
plants, the parts used, and the particular ailments treated.
They take plant specimens and blood
samples to the United States where Joy and Fred work at Baltimore
University Hospital with grants from Phillips Pharmaceuticals,
the National Institutes of Health (a federal agency) and Colco
yourself in the role of one of the investigators. You now have
frozen leaf samples and blood samples in the laboratory. List
some of the initial procedures or experiments that you would undertake.
(5 - 10 minutes)
Group: Share your
list of initial procedure with members of your group. Work together
to combine your lists to be shared with the rest of the class.
Class: Each group
shares its lists so that similarities and differences can be noted.
(Remainder of period)
Joy and Fred have identified six isolates
from the "chemical tea" extract from the noa plant
leaves. A chart appears below. In addition, they have classified
"wasting sickness" as viral in origin and have tentatively
named it wasting sickness virus or WSV. A picture of the virus
is shown below:
|Table of Noa Leaf Chemical Isolates|
|Staphylococcus aureus|| || || || || || |
|Hepatitis B Virus (HBV)|| || || ||
|| || |
|Mumps Virus|| || || || ||
|Breast Cancer|| || || || ||
|Prostate Cancer cells|| || || || ||
|Herpes Virus|| || || ||
|| || |
|Wasting Sickness Virus (WSV)|| || || ||
|| || |
|+ stops growth||- no effect on growth|
What conclusions or inferences can be made form the table and
information given above? An inference is an idea which seems
to be implied in the results but was not tested or observed directly.
An inference can become a hypothesis for a later experiment.
Consider the following scenario which
might have occurred. Joy and Fred Rhodes find that the treatment
of "wasting sickness" contributes to an increased incidence
of miscarriages due to one of the other active ingredients which
is not related to the treatment of "wasting sickness."
The high rate of miscarriages occurs in those women who took
the plant remedy when they were children. Apparently the active
ingredient stays in the system of these children and manifests
its presence when they reach childbearing age. It (the chemical)
contributes to low overall birthrate and a problem with the social
status of the woman's husband . The tribe values children and
a family with only a few children is not considered to be blessed
by their God. Furthermore, none of the other isolates identified
by Joy and Fred has been found to have any significant value in
treating or curing other global diseases or cancers.
Diamond, Jared, "The Arrow of
Disease", Discover, October, 1992.
World Resource Center, May, 1993.
This exercise is designed to be a beginning activity for the first day or two of classes. It can also be used as a problem-solving activity at other points.
It is suggested that you provide a diagram of a virus to represent WSV or "wasting sickness" virus. This can be a modified one of hepatitis B virus since the case data indicate that they are similar. A map of South America would be helpful to show the location of the Amazon.
It is also recommended that you view
the National Geographic film "Secrets of the Amazon"
to get background for this exercise. It portrays the work of
Walter and Memory Lewis, whose experience provided the basis for
this hypothetical model. It can be shown to students at the end
of the activity. Some possible responses are given for Parts
One and Two. This list is not meant to represent the full range
of responses. The questions in the student guides are intentionally
broad. Due to the nature of the Questions in Part Three, no responses