If humanity wants to live on another world, we will first have to terraform it to suit our biology.
Likewise, in order to spread, brain worms would need to find a suitable host to terraform the rest of the species they want to inhabit. They should encourage unhealthy behavior, sow distrust in science, and be in a position of authority.
Hypothesis: RFK Jr died years ago, and is being controlled like an undead meat puppet by brain worms looking to conquer earth.
Turtle with a runny nose.