Avira, do Briskers not teach that hakol b’yedei shamayim except hot and cold?! And when you learn tuma & tahora, you never thought how this is applicable? Please teach your students a simple rule: do not touch mouth, nose, eyes without washing your hands. My Father O’H taught me that, so I thought all learnt Jewish parents do.
Generally, persistent infections are not good for the guf. For example, research shows that untreated dental infections lead to heart problems. Not just statistically speaking, the mechanism I think is already understood. Someone at Touro College is involved in this research.