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EPIDEMIOLOGY 200B
Methods II – Prediction and
Validity
Scott P. Layne, MD
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PART 1
Connecting the Epidemiological,
Medical, and Mathematical Aspects
of Infectious Diseases
March 2010
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As our world grows
So do infectious disease threats
By 2050
Human population of 9 – 10 billion
Emerging Infectious Diseases
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Food Animal Biomass
What is this lecture about?
Three viewpoints on infectious
diseases.
Three methods against infectious
diseases.
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Macroscopic Perspective
Public Health, Epidemiology, Care
Incidence, prevalence, location of infections
(surveillance)
Behaviors, practices that cause infections (investigation)
Infection control measures to reduce impacts
(intervention)
Health policies to reduce impacts (regulation, education)
Care of sick people and populations (drugs, vaccines)
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Microscopic Perspective
Molecular Biology, Immunology,
Pathology
Mechanisms of disease (pathogenesis)
Cellular targets (susceptibility, tropism)
Complexity of agents (genome size)
Heterogeneity of agents (mutations)
Resistance (drugs, vaccines)
Virulence of agents (growth, toxins, adhesions,
regulation)
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Modeling Perspective
Mathematical, Computational Biology
Quantify and analyze variables (parameters)
Improve data collection (limited resources)
Relate complex interactions (nonlinear)
Understand past (validation)
Predict future (forecast, intervention, time scales)
Guide control, elimination, and eradication (intervention)
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Information Domains
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Epitype (outcome)
Time, location
Age, sex, race
Illness severity
Known contacts
Cofactors
Prophylaxis, immunizations
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Phenotype (proteins)
Cross-reactive immunity
Enzymatic activity
Antibiotic resistance
Antiviral resistance
Superantigen
Toxin
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Genotype (DNA / RNA)
Bacteria (large genomes)
Viruses (small genomes)
Whole genomes vs Partial genomes
Pathogenicity islands
Individual open reading frames (orfs)
Regulation
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What Is Life ?
Factor
Humans
Bacteria, Viruses
Reproduction
20 years
1 – 10 hours
Mutation
10-6
10-3 – 10-4
Selection
few
many
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Variola major (smallpox)
Examples of questions that can be addressed
What is the reproductive number for smallpox
What is the optimal outbreak control strategy
What genes and proteins govern virulence
Who should be vaccinated before outbreak occurs
How does the pattern of a natural vs terrorist
outbreak differ
What are benefits and costs of halting air travel to
control outbreaks
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Staphylococcus aureus
(MRSA)
Examples of questions that can be addressed
Risk factors associated with transmission
Optimal schedules for utilizing antibiotics
Impacts of hand washing or other control measures
Are there super-spreaders
What governs spread of virulent clones
What determines ecological fitness
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HIV / AIDS
Examples of questions that can be addressed
Examining and guiding behavioral control programs
Examining and guiding antiviral drug delivery drugs
Optimizing selection of antiviral drugs
Predicting trends and threats in antiviral drug
resistance
Examining efficacy vs impact of vaccines
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Reading
Roy M. Anderson. 2002. The Application of Mathematical
Models in Infectious Disease Research. in Firepower in
the Lab: Automation in the Fight Against Infectious
Diseases and Bioterrorism (S.P. Layne, T.J. Beugelsdijk,
C.K.N. Patel, eds). Washington, DC: Joseph Henry Press,
pages 31 - 46.
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