evidence: Africa Check published an article on 18 May fact-checking another claim that "contagion is a myth" and that germs do not cause disease. We pointed out that this claim is part of a broader set of beliefs known as "terrain theory". [...] Terrain theory, developed by a rival of Pasteur, suggests that germs do not cause disease, and that a person becomes ill because of toxins in their environment, or unhealthy behaviours. The Facebook post even claims that because germs do not cause disease, "there is nothing to be immune to, nor any need for nor existence of an immune system". [...] Gainty said "traces of terrain theory underlie our contemporary obsession with the so-called ‘good’ bacteria of our digestive tract", but that rather than disproving germ theory, these findings have been incorporated into it. "Along the way," she wrote, "germ theory has continued to survive as a theory because it explains so much".