The Atlantic has a long article "How Your Cat is Making You Crazy" on an old Cochranian bug-a-boo: germs that take over the volition of their hosts and make them do stuff that passes along the germ but don't do the host any good, to put it mildly, like making mice attracted to cats.
The crazy cat lady syndrome where a woman ends up with dozens of cats might have something to do with viruses in the cats colonizing her mind and telling her to provide lots of hosts for themselves.
That seems like the ultimate frontier in advertising and marketing. Who knows? Maybe Apple bioengineered a virus that makes people crave shiny Apple products?