1. Conceptual bases

1.1 One Health" concept and systems approach to healthcare

A health phenomenon is the set of changes in the physiological or health status of individuals in a population, for a given pathology or pathology-related trait. It is the result of processes that always depend on numerous parameters.

The personal characteristics of individuals themselves (descriptive traits such as age or sex, biological traits, genetic traits...) have long been the only ones used by biology and medicine to study diseases, but many other parameters concern the relationships between individuals (proximity, contacts, behavioral relationships...), relationships with other living beings, and exposure to their environments (natural, social, economic).

As a result,...