1. Lesson Overview Lesson Overview Fighting Infectious Disease Lesson Overview 35.3 Fighting Infectious Disease

2. Lesson Overview Lesson Overview Fighting Infectious Disease THINK ABOUT IT More than 200 years ago, English physician Edward Jenner noted that milkmaids who contracted a mild disease called cowpox didn’t develop smallpox. At the time, smallpox was a widespread disease that killed many people. Could people be protected from smallpox by deliberately infecting them with cowpox?

3. Lesson Overview Lesson Overview Fighting Infectious Disease Acquired Immunity Dr. Edward Jenner -put fluid from a cowpox patient’s sore into a small cut he made on the arm of a young boy named James Phipps. As James developed mild cowpox. Two months later, Jenner injected James with fluid from a smallpox infection. The boy didn’t develop smallpox. The boy’s cowpox infection had protected him from smallpox infection.

4. Lesson Overview Lesson Overview Fighting Infectious Disease Acquired Immunity Vaccination-The injection of a weakened form of a pathogen, or of a similar but less dangerous pathogen, to produce immunity The term comes from the Latin word vacca, meaning “cow,” as a reminder of Jenner’s work.

5. Lesson Overview Lesson Overview Fighting Infectious Disease Active Immunity Active immunity may develop as a result of natural exposure to an antigen (fighting an infection) or from deliberate exposure to the antigen (through a vaccine). Vaccination stimulates the immune system with an antigen. The immune system produces memory B cells and memory T cells that quicken and strengthen the body’s response to repeated infection.

6. Lesson Overview Lesson Overview Fighting Infectious Disease Passive Immunity Antibodies produced against a pathogen by other individuals or animals can be used to produce temporary immunity. If externally produced antibodies are introduced into a person’s blood, the result is passive immunity. Passive immunity lasts only a short time because the immune system eventually destroys the foreign antibodies.

7. Lesson Overview Lesson Overview Fighting Infectious Disease Passive Immunity Passive immunity can occur naturally or by deliberate exposure. Natural passive immunity occurs when antibodies are passed from a pregnant woman to her fetus (across the placenta), or to an infant through breast milk. For some diseases, antibodies from humans or animals can be injected into an individual. ex.) people who have been bitten by rabid animals are injected with antibodies for the rabies virus.

8. Lesson Overview Lesson Overview Fighting Infectious Disease Acquired Immunity How do vaccines and externally produced antibodies fight disease?

9. Lesson Overview Lesson Overview Fighting Infectious Disease Acquired Immunity How do vaccines and externally produced antibodies fight disease? A vaccine stimulates the immune system with an antigen. The immune system produces memory B cells and memory T cells that quicken and strengthen the body’s response to repeated infection. Antibodies produced against a pathogen by other individuals or animals can be used to produce temporary immunity.

10. Lesson Overview Lesson Overview Fighting Infectious Disease Public Health and Medications In 1900, more than 30 percent of deaths in the United States were caused by infectious disease. In 2005, less than 5 percent of deaths were caused by infectious disease. Two factors that contributed to this change are public health measures and the development of medications. 1.) childhood vaccinations 2.) clean drinking water

11. Lesson Overview Lesson Overview Fighting Infectious Disease Medications Medications are other weapons that can fight pathogens. Antibiotics In 1928, Alexander Fleming noticed that a mold, Penicillium notatum, seemed to produce something that inhibited bacterial growth. Research determined that this “something” was a compound Fleming named penicillin. Researchers learned to mass-produce penicillin just in time for it to save thousands of World War II soldiers.

12. Lesson Overview Lesson Overview Fighting Infectious Disease Medications Antibiotics have no effect on viruses. However, antiviral drugs have been developed to fight certain viral infections. These drugs generally inhibit the ability of viruses to invade cells or to multiply once inside cells.

13. Lesson Overview Lesson Overview Fighting Infectious Disease Public Health and Medications How do public health measures and medications fight disease?

14. Lesson Overview Lesson Overview Fighting Infectious Disease Public Health and Medications How do public health measures and medications fight disease? Public health measures help prevent disease by monitoring and regulating food and water supplies, promoting vaccination, and promoting ways that avoid infection. Antibiotics can kill bacteria, and some antiviral medications can slow down viral activity.

15. Lesson Overview Lesson Overview Fighting Infectious Disease New and Re-Emerging Diseases In recent decades, a host of new diseases have appeared, including AIDS, SARS, hantavirus, monkeypox, West Nile virus, Ebola, and avian influenza (“bird flu”). Other diseases that people thought were under control are re- emerging as a threat and spreading to new areas.

16. Lesson Overview Lesson Overview Fighting Infectious Disease Changing Interactions With Animals Pathogens are also evolving in ways that enable them to infect different hosts. As people clear new areas of land and as environments change, people come in contact with different pathogens.

17. Lesson Overview Lesson Overview Fighting Infectious Disease Changing Interactions With Animals Exotic animal trade, for pets and food, has also given pathogens new opportunities to jump from animals to humans. In 2003, dormice from Ghana spread monkeypox to prairie dogs in the United States, which then infected humans. The spread of SARS also has been associated with the wild animal trade.

18. Lesson Overview Lesson Overview Fighting Infectious Disease Misuse of Medications Misuse of medications has led to the re-emergence of diseases that many people thought were under control. In addition, diseases such as measles are making a comeback because some people fail to follow vaccination recommendations.

19. Lesson Overview Lesson Overview Fighting Infectious Disease New and Re-Emerging Diseases Why have patterns of infectious diseases changed?

20. Lesson Overview Lesson Overview Fighting Infectious Disease New and Re-Emerging Diseases Why have patterns of infectious diseases changed? Two major reasons for the emergence of new diseases are the ongoing merging of human and animal habitats and the increase in the exotic animal trade. Misuse of medications has led to the re-emergence of diseases that many people thought were under control.