The nearest cultural equivalent to these types of parasite are probably beliefs that compromise critical thinking faculties. Probably the most famous of these is the belief that faith is a virtue. Faith - in the sense of belief without evidence - allows a variety of religious memes to thrive which would ordinarily be eliminated by critical faculties. Such memes benefit by association with the "faith" meme. However, the host of a "faith" infection is left with a weakened memetic immune system. This creates an environment in which a wide variety of other counter-factual beliefs can flourish.
In short, faith is the AIDS of the mind.