How a zombie virus became a big biotech business

Sometimes a blog must serve as a repository of regrets, a place to atone for not including some perfect fact in a book. While working on my book Parasite Rex, I came across many delicious examples of parasites manipulating the behavior of their hosts for their own benefit. After the book came out, I met scientists who enlightened me about other examples which would have been wonderful to include. A few years back,  for example, a Johns Hopkins scientist pointed me to a parasitic wasp that turns cockroaches into zombies.

I've recently been wondering about behavior-altering viruses, thanks to an online conversation I had with Ian Lipkin, a virus hunter at Columbia University, about my new book A Planet of Viruses. Lipkin wondered aloud if some viruses would turn out to manipulate their hosts for their own good. Did herpesviruses, for example, increase its transmission by boosting their host's sexual desire?

Most of the examples I knew about came from parasitic animals and fungi. The only virus that could have this kind of effect that I knew of was rabies, which causes its hosts to become more ...