Do cats' transmitting certain diseases contradict the Prophet, peace and blessings be upon him, saying that they are pure and will not defile anything or render it impure?

Cats are pure in body and in their leftover water (su'r), because the Prophet, peace and blessings be upon him, said: "They are not impure; they are among those who circulate among you." If it is established that they transmit diseases, this does not negate their purity. Rather, one must take precautions against them to avoid illness, not due to impurity. If a person is certain that a cat has eaten something harmful or impure, then precautions must be taken against the effect of that on water or food, based on the hadith (definition) "No harm is inflicted nor reciprocated," and the jurisprudential rule "Harm must be removed."