"Occupational disease", as used in this act, unless the context otherwise requires, means any disease that results in disability or death and arises out of and in the course of the occupation or employment of the employee or naturally follows or unavoidably results from an injury as that term is defined in this act. A causal connection between the occupation or employment and the occupational disease shall be established by a preponderance of the evidence.
2. No compensation shall be payable for any contagious or infectious disease unless contracted in the course and scope of employment.
3. No compensation shall be payable for any ordinary disease of life to which the general public is exposed.