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Asthma is an inflammatory disease of the lungs in which the patient’s airways become temporarily constricted, making breathing difficult. Although the condition was virtually unknown in the early 1900s, today it affects 20.3 million people in the United States and kills 5,000 of them per year. From 1980 to 1994, the prevalence of asthma increased 75%. Asthma rates in children under the age of 5 have increased more than 160% in the same time period.
The exact reason for the increased prevalence of asthma is not known, but the following observations offer clues:
- Asthma "attacks" can be triggered by the common cold, exercise, cold air, emotional stress, viral infections, aspirin, industrial air pollutants, smoking, obesity, ozone, and nitrogen dioxide.
- Having two parents with asthma increases a child's chances of having the disease. Approximately 40% of children who have asthmatic parents also develop asthma.
- The disease tends to cluster in England and English-speaking countries.
- Exposure of children to dust mites, cats, cockroaches, molds, and mildews increases their chances of getting the disease.
- Children who are exposed to common parasites seem to have a better-developed immune system than children not exposed to parasites. These exposed children do not suffer asthma as frequently.
- Exposure to occupational agents such as dyes may trigger the onset of adult asthma.
- Poverty seems to be a substantial risk factor for the development of asthma.
- How have the factors that trigger an asthma attack changed since the 1900s? As a researcher, how would you put together the clues given here to explain the emerging epidemic?
- Why do you think Europeans—and especially the English—are most affected by asthma?
- Research the relationship between asthma and allergies. Describe how various agents trigger asthma or an asthma attack.
- Find out where in the world asthma is least prevalent, and hypothesize why this is so.
- Define the word "epidemiology." How do researchers use epidemiology to study a disease such as asthma?
- Research the CDC (Centers for Disease Control and Prevention), which is the epidemiological institution in the United States. Write a two-page paper on the different health problems the organization studies. When might common citizens need to use information from the CDC?
- Visit the CDC website on asthma at http://www.cdc.gov/asthma/default.htm and research the National Asthma Control Program. Find the name and address of agencies in your state that the CDC has funded to fight asthma. Contact one of those agencies to see what is being done in your area.
Asher, M.I., et al. 1998. Worldwide variation in the prevalence of asthma symptoms: The international study of asthma and allergies in childhood. European Respiratory Journal 12:315–35.
Doyle, Roger. 2000. Asthma worldwide. Scientific American, June, 30.
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