John Scalzi, via his AOL Journal By the Way, points out a news report on the Toxoplasma gondii parasite, which has infected an estimated half of the people on this planet. The vector? Cats.
John doesn't quote it directly in his post, but if you follow his link to the original article and read all three pages, you'll come to this cheery bit of news:
Cat lovers need not get rid of their cats. The chances are not great that a modern cat, kept on a diet of safe cat food and not left to feed off rats, will transmit the parasite to humans. It's possible, but not likely, Lafferty says.
Whew! Good to know.