Jared Diamond describes a case of a man having "visited the farm" and then being ill with fever. Diamond cited the case as a possible transfer of "crowd disease

Jared Diamond describes a case of a man having "visited the farm" and then being ill with fever. Diamond cited the case as a possible transfer of "crowd diseases", originated in animals, to humans. "Guns, Germs and Steel", Jared Diamond. EDIT: horizontal disease and horizontal gene transfer are very powerful forces in evolution. The distribution of human populations on Earth today owe a lot to such crowd diseases (whatever the means by which they got into humans from animals; inhalation of sprayed out rhinoviruses or eating raw meat has been proven sufficient in cases.)