Causal Relationships

Question 1

Henle-Koch Postulates

Answer 1

1) organism must be present in every case o the disease
2) organisms must be able to be isolated and grown in pure culture
3) organism must CAUSE the specific disease
4) organism must then be re-isolated from the experimentally infected animal

Question 2

Necessary Cause

Answer 2

The exposure must be present in order for the disease to occur

Question 3

Sufficient Cause

Answer 3

the exposure on its OWN is all that is needed in order for disease to develop

Question 4

Several factors are necessary for disease to develop, but no single exposure alone is enough to cause disease

Answer 4

Necessary, but not sufficient

Question 5

A single factor alone can result in disease development, but so can other factors/exposures

Answer 5

Not necessary, but sufficient

Question 6

A group of paired exposures can cause disease, but if one pair is eliminated - the others can still cause disease

Answer 6

Not necessary nor sufficient

Question 7

Bradford Hill’s Criteria (9)

Answer 7

strength of association, consistency, specificity, temporality, biological gradient, biological plausibility, coherence, experiment, analogy

Question 8

Exposure is present and causes disease

Answer 8

necessary and sufficient