Epidemiology is concerned with the incidence of disease in populations and does not address the question of the cause of an individual's disease. This question, sometimes referred to as specific causation, is beyond the domain of the science of epidemiology.
Ninetales is the evolved form of Vulpix, who evolves by the use of a Fire Stone, while Alolan Ninetales is evolved with an Ice Stone.
Tuvix was a hybrid being created as the result of a transporter accident on the USS Voyager, combining Lieutenant Tuvok, Neelix, their uniforms, and an orchid in 2372. The accident was the conclusion to an away mission to collect some orchid samples.