ch 17: microbiology

Chapter 17: Immunization and Immune Testing

Overview of Immunization Methods

  • Active Immunization

    • Definition: Body creates its own antibodies.

    • Long-term protection through memory B and T cells.

  • Passive Immunization

    • Definition: Antibodies are transferred from another person to provide immediate protection.

    • No long-term immunity generated; only current protection.

Vaccine Case Studies

  • Polio

    • 1950s: High incidence of polio cases.

    • Introduction of vaccines led to eradication in the U.S.

    • Still more common in other parts of the world.

  • Measles

    • High cases reported in the 1950s-1970s.

    • Vaccine introduction drastically reduced cases, almost to zero.

    • Remaining cases primarily among unvaccinated individuals due to personal beliefs.

  • Smallpox

    • Eradicated globally; historical importance.

    • Variolation: Early method using infected scabs to inoculate.

      • Used in China during early 1700s.

    • Edward Jenner developed smallpox vaccine.

      • Used cowpox scabs to trigger immune response.

Herd Immunity

  • Definition: Protection of unvaccinated individuals due to high vaccination rates in the community.

  • Importance in controlling infections, especially for vulnerable populations.

  • Example: During the COVID-19 pandemic, herd immunity played a role in protecting unvaccinated individuals.

Types of Vaccines

1. Active Immunity: Types of Vaccines

  • Attenuated (Modified Live) Vaccines

    • Live microbes with reduced virulence.

    • Examples: Chickenpox, MMR (measles, mumps, rubella), BCG (for TB).

    • Shed mild forms of the virus, potentially infecting others (contact immunity).

  • Inactivated (Killed) Vaccines

    • Microbes are killed (using heat or formaldehyde) and require adjuvants to elicit immune response.

    • Examples: Rabies, anthrax, pertussis.

    • Require boosters for ongoing protection.

  • Subunit Vaccines

    • Only portions of the microbe are used.

    • Examples: Pertussis, hemophilus influenza B (Hib), HIV vaccine.

  • Toxoid Vaccines

    • Inactivated toxins used in immunization.

    • Examples: Diphtheria, tetanus.

    • Require boosters; provide long-lasting protection.

2. Combination Vaccines

  • Administering multiple vaccines simultaneously.

  • Examples: DTaP (diphtheria, tetanus, pertussis), MMR, Pentacel (DTaP, Hib, polio).

Passive Immunotherapy

  • Definition: Transfer of antibodies for immediate protection.

  • Advantages:

    • Immediate defense without the waiting period for active immunity.

  • Disadvantages:

    • Lack long-term immunity as no memory B and T cells are created.

    • Risk of allergies to transferred antibodies (serum sickness).

  • Beneficial for individuals with immune system deficiencies (e.g., DiGeorge syndrome).

Conclusion

  • Immunization and immune testing play crucial roles in public health.

  • Understanding different types of immunity and vaccines is essential for effective disease prevention and control.