Table 1.

Prevalence, causation, and complexity of diseases.

A. Factors affecting the prevalence and severity of infectious diseases.

• Climatic factors

• Social conditions

• Molecular variations in pathogens

• Dynamic of the vector agent

• Genetics of the host population

• Interactions with concurrent diseases

B. Cause vs. causal association.

→ Cause

• any factor that produces an effect

• in medicine, also reported as etiology, pathogenesis, mechanism.

→ Causal association

• any factor that reveals an increased frequency of association in exposed vs. non-exposed

• in medicine, a factor associated is a risk factor.

C. Complexity of individual adaptation.

There are many degrees of freedom:

• the initial condition is uncertain

• the sensitivity/susceptibility is individual

• the future exposure to the environment depends on space-time

• different systems are dynamically involved

• the results may be of opposite sign, unfavorable, neutral, or even favorable.