Lec_3_Viruses - Basic Epidemiological Concepts and Terms...

Info iconThis preview shows pages 1–11. Sign up to view the full content.

View Full Document Right Arrow Icon
Basic Epidemiological Concepts and Terms Incidence: # of new cases of disease/total # at risk. Incidence rate: Incidence/unit of time. Cumulative Incidence: Incidence measured over longer period Prevalence: # cases (or # with defined condition) existing at specific time. Prevalence rate: # of such cases/total # at risk.
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Basic Epidemiological Concepts and Terms Risk - The number of individuals who are exposed and become ill divided by the number of those exposed Relative Risk - The risk of illness for individuals exposed divided by the risk of illness for those not exposed
Background image of page 2
Example # Ill that did eat Total # eating # Ill that did not eat Total # not Eating Quiche 2 10 3 5 Cheesecake 4 5 1 10 Swiss Roll 3 7 2 8 Chocolate Cake 1 3 4 12 Cheese Dip 4 11 1 4 What Are Relative Risks for Each Food Item??? Food Relative Risk Quiche 0.33 Cheesecake 8 Swiss Roll 1.72 Chocolate Cake 0.93 Cheese Dip 1.44
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Basic Epidemiological Concepts and Terms Odds for Cases - Number of cases exposed to a factor divided by the number of cases not exposed to the factor Odds for Controls - Number of controls exposed to a factor divided by the number of controls not exposed to the factor Odds Ratio - Odds for cases divided by odds for controls OR = O cases /O controls
Background image of page 4
Example Cases Controls Exposed a b Not Exposed c d What is Odds Ratio??? OR = (a/c)/(b/d) = ad/bc
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Koch’s Postulates Organism must be consistently present in diseased state Organism must be isolatable and culturable Cultured organism must induce disease when introduced to susceptible host
Background image of page 6
Basic Epidemiological Concepts and Terms Confounding- when a factor is associated with the exposure one is studying and which at the same time is associated with the outcome Causation- nine criteria outlined by Sir Austin Bradford Hill in 1965. Strength (is the risk so large that we can easily rule out other factors) Consistency (have the results have been replicated by different researchers and under different conditions) Specificity (is the exposure associated with a very specific disease as opposed to a wide range of diseases) Temporality (did the exposure precede the disease) Biological gradient (are increasing exposures associated with increasing risks of disease) Plausibility (is there a credible scientific mechanism that can explain the association) Coherence (is the association consistent with the natural history of the disease) Experimental evidence (does a physical intervention show results consistent with the association) Analogy (is there a similar result that we can draw a relationship to)
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Dynamic Population Model SIR Model (n = S + I + R) S= Susceptibles I= Infectious R=Resistants
Background image of page 8
Viruses
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
" Virus
Background image of page 10
Image of page 11
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

Page1 / 73

Lec_3_Viruses - Basic Epidemiological Concepts and Terms...

This preview shows document pages 1 - 11. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online