Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
49 40 o5 1 0 -m i n u t e s es si A Y -t on An Ounce of Prevention L ROLE P ACTIVIT Y OVERVIEW SUMMARY Small groups of students participate in a role play. In the first scene, they learn about how vaccinations work to protect people against viral and bacterial illnesses. In the second scene, they are introduced to the use and misuse of antibiotics. KEY CONCEPTS AND PROCESS SKILLS 1. Making decisions about complex issues often involves trade-offs (i.e. giving up one thing in favor of another). 2. Most infectious diseases are caused by microbes. 3. The category of “microbes” includes microorganisms, such as bacteria and protists, and also viruses, which are not considered to be alive. 4. The human body has natural defenses against infectious diseases. These include barriers such as skin, linings such as mucus, and white blood cells in the immune system. 5. Vaccines help the body build immunity against some viral and bacterial diseases. When a person is later exposed to that disease, he or she is protected from catching it. 6. Antibiotics are effective against many bacterial infections, but not against viral infections. KEY VOCABULARY antibiotic immune system bacteria microbe cell trade-offs disease virus evidence vaccination Teacher’s Guide C-243 Activity 49 • An Ounce of Prevention MATERIALS AND ADVANCE PREPARATION For the class * props, such as a lab coat, hat, set of scrubs/surgical clothes, stethoscope, pale make-up (for the sick person), etc. (optional) * video camera (optional) *Not supplied in kit Collect props if you will be using them. n Teacher’s Note: Decide if you wish all students to perform the role play in groups of four. Another alternative is to assign the role play to one group to practice and present to the class. This may be a group of students ahead with their work or some students who have trouble with written assignments but excel at performing. Because of the complexity of the two major ideas contained within the role play (vaccination and antibiotics), you may wish to introduce, perform, and discuss Scene One during one class period and then move on to Scene Two in a second session. TEACHING SUMMARY Getting Started 1. Students brainstorm ways to prevent infectious diseases. Doing the Activity 2. Students read the role play aloud. Follow-Up 3. Review key concepts with the class. Extension Students can interview different generations of adults to find out if they can recall knowing anyone who had polio. INTEGRATIONS Language Arts/Drama Acting out the role play will aid student comprehension of subject matter and allow individual expression. Interested students can practice and then perform a scene for the class (either in person or on videotape). C-244 Science and Life Issues An Ounce of Prevention • Activity 49 BACKGROUND INFORMATION Flu The flu is caused by a variety of related viruses. Flu viruses are highly mutable and each flu season can produce a new strain of the flu. Each year, the flu causes an average of 20,000 deaths in the U.S., mostly among the elderly. Some flu strains, such as the Spanish Flu of 1918, are more lethal than others. There have been two other flu epidemics since the 1918 outbreak, one in 1957 and one in 1968. The 1968 epidemic caused 50,000 deaths in the U.S. Other potentially lethal strains of the flu have been identified, most recently in 1998 when individuals exposed to chickens in Hong Kong became seriously ill from a flu that originated in the chickens. All of the chickens in Hong Kong were destroyed as a result, and the spread of the infection was contained. Today, a global flu surveillance network monitors the emergence of new flu strains. Due to advances in treatment and prevention, the death toll in the U.S. from future flu outbreaks is unlikely to be as high as in 1918 or 1968. However, because the flu virus is so mutable, there remains a real possibility of a global epidemic. Today, the flu can often be prevented with a vaccine. The flu vaccine is made from killed virus and cannot cause the flu. Flu vaccinations reduce the likelihood of catching the flu. Each year, new versions of the flu vaccine are developed, based on which strains of the flu are predicted to be the most prevalent. Flu vaccinations are inexpensive and have few side effects. (During the late 1970s, the nervous disorder “Guillain Barre” was caused by impurities in the flu vaccine. Since then, better purification methods have been developed.) People who have received the vaccine and who then catch the flu usually have a less severe illness. Elderly and immuno-compromised people are considered to be at greater risk of having severe flu infections. These individuals and individuals who may come into contact with them are encouraged to get vaccinated against the flu. The flu vaccine is not recommended for children. Although the flu is a viral disease, antibiotics have helped reduce the death rate when complications occur and a bacterial infection sets in. A lung infection or pneumonia is the major cause of death from the flu. The flu strips the lining of the bronchi and makes the lungs vulnerable to attack by bacteria. Bacterial pneumonia can be treated with antibiotics. Vaccines Since vaccines are made of either weakened whole viruses or parts of the virus, the development and sale of vaccines require the approval of the U.S. Food and Drug Teacher’s Guide C-245 Activity 49 • An Ounce of Prevention Administration. The weakened viruses are made by exposing the viruses to chemicals or heat and then purifying the weakened viruses and putting them into a non-toxic solution. Vaccines such as live, weakened polio vaccine tend to be more effective at stimulating the immune response but have a very slightly higher risk of side effects. (For this reason, the Centers for Disease Control and Prevention recommended a return to the killed polio vaccine as of January 1999.) Vaccines are available for many infectious diseases caused by both bacteria and viruses. In the United States, recommended childhood immunizations include diphtheria, tetanus, pertussis, hepatitis B, polio, haemophilus influenzae type b, measles, mumps, rubella, and varicella (chicken pox). Hepatitis A vaccine is recommended for children and adolescents at high risk for hepatitis A infection. Pneumococcal vaccine and annual influenza vaccine are recommended for children and adolescents at high risk. International travelers often need additional vaccinations, such as for yellow fever and cholera, depending on where they are going. Vaccinations are not available for all contagious illnesses—the common cold, AIDS, Ebola, Hanta, and other emerging diseases do not yet have vaccines developed against them. Diseases caused by protists, such as malaria, and diseases caused by worms, such as river blindness, cannot be prevented by vaccination. Although a vaccine for the flu does exist, it is not currently 100% effective because of the ability of the flu virus to mutate quickly. Vaccination programs for children in the United States, along with an increase in the standard of living and improved sanitation, have been responsible for a tremendous reduction in childhood death and disability. However, vaccination has not replaced the need for good hygiene and sanitation. In the U.S., growing public resistance to getting required vaccinations is becoming a public health issue. Possible reasons for this are that people no longer remember how serious vaccine-preventable diseases once were and they perceive the risk of vaccination as greater than the risk of infection. This perception may be due to some serious side effects of vaccines in the past. Current vaccines are closely monitored over millions of doses. The very small risk of side effects is generally considered to be outweighed by the risk of catching the disease. C-246 Science and Life Issues An Ounce of Prevention • Activity 49 TEACHING SUGGESTIONS GETTING STARTED 1. Students brainstorm ways to prevent infectious diseases. otics, and introduces the use and misuse of antibiotics. The importance of antibiotic use and misuse is further developed in activities later in the unit. Have students read Scene One in their groups of four. Students can choose or be assigned a specific role within their group. If you provide each student Ask students to work in groups of four to brainstorm with a photocopy of the student pages, each student answers to the question, How can infectious dis- can pencil in the appropriate names where required eases be prevented? Circulate and listen to group as well as highlight their lines. Provide any props discussions. Students are likely to raise concepts of that you have available. hygiene, sanitation, and vector control. Allow time for students to complete Scene One. Ask the class, What diseases have you been vacci- Then invite one or two groups to present their ren- nated against? Students are likely to remember vac- dition of the role play to the class. cines such as polio, rubella, measles, whooping cough, diphtheria, etc. Repeat these steps for Scene Two. FOLLOW-UP Have students read the Introduction on page C-90 in the Student Book. Help them relate the role of the immune system, as presented in Activity 46, “Dis- 3. Review key concepts with the class. ease Fighters,” to how vaccines might work. The Spend time reviewing with the class the difference role play will reinforce this idea. between an antibiotic and a vaccination. Student responses should include that a vaccination is a way DOING THE ACTIVIT Y 2. Students read the role play aloud. to prevent some bacterial or viral illnesses and an antibiotic is a way to treat bacterial infections only. Antibiotics are not effective against viral illnesses. The first scene in the role play teaches students more You may wish to use a table to summarize these about vaccination. The second scene addresses the points, as shown below. common confusion between vaccination and antibi- Prevention or Treatment? Effective Against Can Help Treat Vaccination prevention viruses, bacteria flu, measles, tetanus, diphtheria, polio, etc. Antibiotics treatment bacteria diphtheria, some types of pneumonia Teacher’s Guide C-247 Activity 49 • An Ounce of Prevention To foreshadow Activities 51, “The Full Course,” and n Teacher’s Note: The theme of prevention vs. 52, “Miracle Drugs—Or Not?” ask students, Why treatment was first raised in the activities on might doctors prefer to test for bacteria first, heart disease in Unit B “Body Works,” of Science instead of prescribing antibiotics right away? and Life Issues. The same question is now asked Responses may include cost and possible side effects in the context of infectious diseases. Many of of unnecessary medications. Some students may the principles are the same. have ideas about antibiotic resistance, which is 2. brought up in these later activities. n Teacher’s Note: Analysis Question 4 could be used Chemicals or heat are used to inactivate the virus before it is used in a vaccine. A vaccine is as a debate question for the class, or a discussion typically a dead or weakened form of the dis- question for groups of four. Alternatively, you can ease-causing microbe or parts of the disease- assign individual students to write the answer and causing microbe. then you can assess with the “Using Evidence to Make Trade-offs” element of the E V I D E N C E AND Why are serious side effects from vaccines very rare? 3. You go to the doctor and find out that you may have T R A D E - O F F S (ET) variable. You may want to have the flu. Would you expect to be prescribed an antibi- students review the ideas presented earlier in this otic? Explain your answer. unit. Analysis Question 5 is identical to a question The flu and colds are caused by viruses. Antibi- first posed in Activity 32, “Who Infected Whom?” otics are not generally prescribed against viral Extension infections because they are not effective. Students should not routinely expect antibiotics to Students can interview different generations of treat colds or flu. (In some cases, when people adults to find out if they can recall knowing anyone have low resistance, antibiotics are prescribed who had polio. to prevent a bacterial infection from setting in. For example, in cases of viral pneumonia, SUGGESTED ANSWERS antibiotics are sometimes prescribed, not to TO ANALYSIS QUESTIONS 1. cure the existing viral pneumonia, but as a pre- A vaccine prevents the individual from ventive measure to ensure that a bacterial infec- catching an infectious disease; it does not tion does not start.) treat the disease after the person has caught it. What are some advantages of preventing, rather than treating, infectious diseases? Advantages to prevention include reduced suffering (e.g., physical, emotional, time lost from work and family, etc.) and reduced expense (e.g., hospitalization, medication, etc.). 4. Do you think that vaccinations against the flu should be required? Explain. Support ET uet your answer with evidence and identify the tradeoffs of your decision. Hint: To write a complete answer, first state your opinion. Provide two or more pieces of evidence that support your opinion. Then consider all sides of the issue and identify the trade-offs of your decision. C-248 Science and Life Issues An Ounce of Prevention • Activity 49 • Complete and correct level 3 responses are that otherwise wouldn’t. But you shouldn’t shown below: force people to do things like get a shot I think vaccinations should be required. against a disease that isn’t that serious. Vaccines help your immune system fight infectious diseases. Giving people vaccines would reduce the chance that they would 5. Reflection: Explain whether you would change your answer to Question 4 if the disease had more severe symptoms and a greater chance of causing death. catch the disease. If fewer people had the • disease, then fewer people would get sick. Some students who said no to Question 4 may Every time I get the flu, I miss almost a whole say yes to Question 5 due to the greater severi- week of school, and it’s so hard to make it up. ty of the symptoms. In fact, most students have The trade-off is that vaccines do not always had vaccinations against polio and other seri- work 100% and you might have to force ous diseases. people to get a vaccination against their will. This question raises some of the criteria used in People hate to get shots. making decisions about public health policy. Vaccines against the flu shouldn’t be required. The seriousness of the disease and the possibil- First of all, it’s not a very serious disease for ity of serious complications are two factors most people. Second, you can still get the flu involved in decisions about vaccinations. As even if you have the vaccination. And there more vaccinations are developed, students may might be side effects to the vaccination. be required to have additional vaccinations in Unfortunately, some people might get the flu order to attend school. Teacher’s Guide C-249