Fighting Infectious Disease

Document Sample
Fighting Infectious Disease Powered By Docstoc
					Lesson Overview   Fighting Infectious Disease




                                     Lesson Overview
                                              35.3 Fighting
                                           Infectious Disease
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?
Lesson Overview         Fighting Infectious Disease


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


  Acquired Immunity
     Dr. Edward Jenner performed an
     experiment in which he 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 expected, 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.
Lesson Overview          Fighting Infectious Disease


  Acquired Immunity
     The injection of a weakened form of a pathogen, or of a similar but less
     dangerous pathogen, to produce immunity is known as a vaccination.

     The term comes from the Latin word vacca, meaning “cow,” as a reminder
     of Jenner’s work.
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.
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.
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.

       For example, people who have been bitten by rabid animals are injected
       with antibodies for the rabies virus.
Lesson Overview         Fighting Infectious Disease


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


  Public Health Measures
       In 1854, Dr. John Snow learned, through interviewing residents
       and mapping, that the source of a London cholera outbreak was
       a water pump. This is a major event in the history of public
       health.

       The field of public health offers services and advice that help
       provide healthy conditions.
Lesson Overview         Fighting Infectious Disease


  Public Health Measures
       Promoting childhood vaccinations and providing clean drinking water
       are two important public health measures that have greatly reduced the
       spread of infectious disease.
Lesson Overview          Fighting Infectious Disease


  Medications
       Medications, such as antibiotics and antiviral drugs, are other weapons
       that can fight pathogens.

       An antibiotic is a compound that kills bacteria without harming its host.

       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.
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.
Lesson Overview         Fighting Infectious Disease


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


  New and Re-Emerging Diseases
     By 1980, many people thought that medicine had conquered infectious
     disease.

     Vaccination and other public health measures had wiped out polio in the
     United States and had eliminated smallpox globally.

     Antibiotics seemed to have bacterial diseases under control.

     Some exotic diseases remained in the tropics, but researchers were
     confident that epidemics would soon be history.
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.
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.
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.
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.

       For example, many strains of the pathogens that cause tuberculosis and
       malaria are evolving resistance to a wide variety of antibiotics and other
       medications.

       In addition, diseases such as measles are making a comeback because
       some people fail to follow vaccination recommendations.

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:68
posted:9/15/2012
language:Unknown
pages:23