This is what we're talking about when we at Second Thoughts write that West Nile virus is something to watch out for.
The short story: A horse in Tracy died from the virus.
The bad news: That means the virus is alive and well in the south county.
The good news: Horses are much more likely to get a severe case of the bug than humans, according to the CDC. It's only about 1 in 150 infected humans that contract a bad form of the disease, and not all of those are doomed.
So don't go into conniptions every time one of the little buggers sucks your blood. Just use common sense if you feel ill. And some of this.