Maybe there is a 2nd virus or a parasite that affects their host to behave in weird ways.
[io9.gizmodo.com]
One of many videos:

I have an old friend who fell prey to that cult. I had to break off the friendship completely and finally. It is so toxic and so weird that I can't fathom how anyone could believe in it, and yet it is curiously like the movie "The Invasion of the Body Snatchers". One day your friend is your friend, the next she is some alien creature who believes Democrats drink the blood of children. I'm still trying to figure out what type of personality is most vulnerable, and why my friend became a victim, and is now victimizing others. She has lost relationships with her children, grandchildren, a niece, and friends. Who would do that? Oh, BTW, my ex-friend is the daughter of a Holocaust survivor.