6. Causation (or causality) deals with the relationship between cause and WHAT
effect
reaction
7. Indirect cause of disease:
an intervening variable that affects the disease
what is traditionally considered a causal relationship; direct response from the causal factor disease/outcome
8. WHAT: exert a major effect in inducing disease. Often necessary causes…
primary cause
necessary cause
sufficient cause
9. Precipitating factors:
facilitate manifestation of a disease
associated with the definitive onset of disease
tend to aggravate the presence of a disease
increase the level of susceptibility in the host
10. Reinforcing factors:
tend to aggravate the presence of a disease
facilitate manifestation of a disease
increase the level of susceptibility in the host
associated with the definitive onset of disease
11. WHAT: a cause that produces an effect, e.g. pneumonia in calves (viral infection secondary bacterial infection & suboptimal environmental factors)
necessary cause
sufficient cause
primary cause
12. WHAT: one without which the disease will not occur, e.g. Mycobacterium tuberculosis paratuberculosis
