1. Section 21.4 Emerging Infectious Diseases Slide 1 of 15 Objectives Define the term emerging disease. Identify five reasons why diseases emerge. Section 21.4 Emerging Infectious Diseases

2. Section 21.4 Emerging Infectious Diseases Slide 2 of 15 Health Stats The map shows how dengue fever, a viral disease carried by mosquitoes, has spread since 1960. Should the United States be concerned about dengue fever? Explain.

3. Section 21.4 Emerging Infectious Diseases Slide 3 of 15 An epidemic (ep uh DEM ik) is an unusually high occurrence of a disease in a certain place during a certain time period. What Is an Emerging Disease? When an epidemic affects many areas of the world, it is sometimes called a pandemic. An emerging disease is an infectious disease that has become increasingly common in humans within the last 20 years or threatens to become more common in the near future.

4. Section 21.4 Emerging Infectious Diseases Slide 4 of 15 Click above to go online. For: Updates on modern epidemics

5. Section 21.4 Emerging Infectious Diseases Slide 5 of 15 Diseases can emerge when humans come into contact with infected animals; pathogens become resistant to existing drugs; or people lack appropriate immunizations. Why Do Diseases Emerge? The increased frequency of international travel and a global food supply can enable emerging diseases to spread very quickly.

6. Section 21.4 Emerging Infectious Diseases Slide 6 of 15 Some diseases that are common in animals can spread to humans. Contact With Infected Animals There have been recent cases in Asia in which people have become sick after being exposed to infected birds. Scientists fear that another deadly flu epidemic could result if the virus takes on a form that can spread easily between people.

7. Section 21.4 Emerging Infectious Diseases Slide 7 of 15

8. Section 21.4 Emerging Infectious Diseases Slide 8 of 15

9. Section 21.4 Emerging Infectious Diseases Slide 9 of 15 Some diseases are caused by pathogens that can mutate, or change, over time. Drug Resistance Sometimes these mutations result in a strain, or type, of pathogen that no longer responds to medicine.

10. Section 21.4 Emerging Infectious Diseases Slide 10 of 15 Diseases that were common many years ago can pose a threat again if people don’t get the proper immunizations. Lack of Immunization The polio virus remains a threat in several Asian and African countries because many people in those countries have not received the vaccine.

11. Section 21.4 Emerging Infectious Diseases Slide 11 of 15 Globalization refers to the fact that people around the world are no longer geographically isolated from each other. International Travel Not only can people travel much more easily, but so can any pathogens that live in their bodies. World travelers could spread the pathogen around the world in a short amount of time.

12. Section 21.4 Emerging Infectious Diseases Slide 12 of 15 Food also travels around the world. Global Food Supply If a pathogen is present in a food product, it can spread quickly.

13. Section 21.4 Emerging Infectious Diseases Slide 13 of 15 Vocabulary epidemicAn unusually high occurrence of a disease in a certain place during a certain time period. emerging diseaseAn infectious disease that has become more common within the last 20 years or threatens to become more common in the near future.

14. Section 21.4 Emerging Infectious Diseases Slide 14 of 15 QuickTake Quiz Click to start quiz.

15. Section 21.4 Emerging Infectious Diseases Slide 15 of 15 Click above to go online. For: Chapter 21 self test

16. Section 21.4 Emerging Infectious Diseases Slide 16 of 15 End of Section 21.4 Click on this slide to end this presentation.