I either read a story or saw a show where the beings of a planet were asking for help. The doctors went down and couldn’t find anything wrong except an “infection” in the host. Turns out that the “infection” in the host was a collective bacteria that WAS the intelligence in the being and without the bacteria, the host was a dumb animal. What the bacteria needed was a way to suppress the immune system so that they could live in the host better.
Were the author writing about humans? ;^)
Not humans in general, just liberals.