How to understand the proverb that disease is at enmity with purity?

Cleanliness means washing your hands before eating, before and after visiting the toilet, washing fruits and vegetables, not putting fingers, pens, pencils in your mouth – which are simply teeming with bacteria, any of which can cause infection, use clean, washed dishes. And if we observe cleanliness, then bacteria will have nowhere to come from and infection will not happen. That is why disease is not friendly with cleanliness.