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Name ____________________________________ Date __________ Class ___________________
SECTION 8-3
ENRICH
Fighting a Viral Disease
Before the 1960s, severe outbreaks of the disease poliomyelitis occurred in many
parts of the world. This disease, also known as “infantile paralysis” or simply
“polio,” infected mostly children. However, it was capable of attacking adults as
well. One of the most famous victims of polio was United States President
Franklin Delano Roosevelt, who got the disease as an adult.
Polio is transmitted from person to person, usually by inhaling droplets infected
with the virus. It can paralyze the arms or legs of a person or the muscles that
control breathing and can even cause death.
The graph shows the history of polio in South America, Central America, and
North America from 1954 to 1973. In the 1990s, polio was eliminated in the
Americas.
Polio in the Americas
12
Introduction of
Salk vaccine
Cases per 100,000 People
11
10
Introduction of
Sabine vaccine
9
8
7
N orth America
6
5
South America
4
Central America
3
2
1
1958
1962 1966
Year
1970
Answer the following questions on a separate sheet of paper.
1. What was used in an attempt to fight the spread of polio?
2. In 1954, about how many cases of polio per 100,000 people were there in
South America? Central America? North America?
3. In 1972, about how many cases of polio per 100,000 people were there in
South America? Central America? North America?
4. Compare the three lines of the graph. What is the most obvious difference
among them? Write a hypothesis to explain the difference.
48
U nit 3 Reso urces
Scie nce Explorer Focus o n Lif e Scie nce
© Prentice-Hall, Inc.
1954