midterm-3-review-summary-infectious-disease-dynamics

Midterm 3 Review - Summary Infectious Disease Dynamics

Page 1

• Overview of the course material covered in the midterm with focus on infectious disease dynamics.

• Emphasizes the importance of understanding infection transmission and immunity.

Page 2 - Key Concepts of Infectious Disease Dynamics

• Core Rates and Durations:

  • Infection Rates: 1/rate = average duration in that compartment.

  • Waning Immunity: Average time of immunity is 1/delta.

• Relative Susceptibility:

  • Individuals infected previously may exhibit reduced susceptibility; ε indicates the degree of susceptibility.

  • Susceptibilities and transmissibilities gauge from 0 (never susceptible) to 1 (fully susceptible, SIR model).

• Transmission Dynamics:

  • Strength of immunity, non-pharmaceutical interventions (NPIs), and seasonal factors crucial in transmission peaks.

  • The first infection peak remains unaffected by immunity strength.

  • Secondary infections can lead to larger peaks due to accumulation and seasonality.

• Vaccination Impact:

  • Durable vaccines reduce severe cases and susceptibility.

  • Variation in vaccine uptake can affect herd immunity thresholds.

Page 3 - Evolution and Transmission

• Natural and Vaccine-induced Immunity:

  • A low viral abundance with natural infection and high immune pressure fosters pathogen adaptation.

  • High adaptation is evident under intermediate immune pressure.

• Diversity and Evolution:

  • Equity in vaccination uptake influences evolutionary potential.

  • Fast waning immunity accelerates evolution; low equity causes high evolutionary necessity for boosters.

• Accumulation Effects:

  • Accumulation of immune individuals modifies susceptibility, impacting future infection dynamics.

Page 4 - Transmission Heterogeneity

• Variation in Infection Transmission:

  • Individuals exhibit varied capable transmission, leading to a distribution of infections (Superspreaders).

  • The 80-20 rule indicates that a small fraction of cases can lead to the majority of transmissions.

• Stochastic Models:

  • Randomness and individual variation critical in disease spread; stochastic processes highlight probabilities in outbreak potential.

Page 5 - Disease Control Strategies

• Targeting Superspreaders:

  • More effective to control infections at the superspreader level than through population-wide measures.

  • Individual-specific controls increase variation in infection potential, effectively reducing spread likelihood.

• R0 Relation:

  • R0 informs control strategy effectiveness—higher R0 requires higher vaccination coverage.

Page 6 - Historical Context and Antibiotics

• Impact of Vaccination and Antibiotics:

  • Significant decrease in infectious diseases with antibiotics and vaccines; social conditions continue to play a vital role.

  • The historical rise of antibiotic resistance emphasizes the need for evolution-aware interventions.

Page 7 - Resistance Evolution

• Mechanisms of Resistance:

  • Plasmid transfer among microbial strains enhances resistance; not limited to pathogens alone.

  • Agricultural antibiotic use contributes to the development of resistant strains in human pathogens.

• Mitigation of Resistance Spread:

  • Solutions focus on minimizing antibiotic usage and employing multiple drug therapies to counter resistance evolution.

Page 8 - Antibiotics and Resistance Management

• Drug Application Strategies:

  • Simultaneous multi-drug application considered more effective than sequential approaches in minimizing resistance.

  • Ongoing exploration for new agents for combating resistance.

Page 9 - Role of the Microbiome

• Microbiome and Immune System Interactions:

  • Microbiome critical in shaping immune responses; regulates tolerance and perception of pathogens.

  • Dysbiosis linked to disease symptoms yet remains complex in causation versus correlation.

Page 10 - Microbiome Influences on Immunity

• Critical Role of Microbiome:

  • Microbiome composition significantly influences immune responses and susceptibility to infections.

• Transplantation Experiments:

  • Fecal transplants demonstrate the microbiome's role in immune modulation.

Page 11 - Holobiont Concept

• Defining Holobionts and Hologenomes:

  • Emphasizes interdependence between hosts and their microbial communities while recognizing the role of early exposure in immune tolerance development.

• Critical Windows of Immune Response:

  • Timing of microbiome exposure influences immune system education regarding self-versus-non-self recognition.

Page 12 - Summary of Critical Research Findings

• Implications for Health:

  • Understanding the microbiome and its interactions with pathogens and the immune system is vital for designing effective interventions.

  • Further research necessary to clarify roles of microbiota in health and disease management.