"It is wide spread, this is the worst year ever for West Nile virus, 700 confirmed cases, estimates that 12,000 have already been sickened. It's in 43 states," said ABC News Medical Editor Dr. Richard Besser.
West Nile usually affects the elderly or unhealthy. In fact, most people never even know they have it. Dr. Besser talks about precautionary measures -- that's coming up on Good Morning America, right after this newscast at 7 a.m.