West Nile is not a particularly virulent bug for most people, and indeed, if you live in 'skeeter country- like we do- you may well have already been exposed. I would not, however, dismiss utterly the idea that it may have been deliberately introduced to study how well & far it vectors.
Our tinfoil hats must be wired together via the 'net : )
Similar "experiments" have been tried. I recall a show I saw on one of the Discovery Channel-type stations. Scientists exposed a large number of mosquitoes to a certain type of radiation and released them in a certain area. Special traps were set up some distance from the release point to capture the irradiated buggers. A Geiger counter (or something similar) was used to scan the bugs to see how far and at what patterns they traveled. I don't remember much more of the specifics. Although the radiation level in these skeeters was harmless, and it may have been a viable experiment, this whole story made me wonder what else the CDC does that we don't know about.
I was reluctant to write this, since I could catch some flak from certain people who are CONVINCED that Sadaam is behind the WNV (who knows-he could be), and that the benevolent CDC, under the careful watch of GWB would even contemplate releasing infected mosquitoes among the populace. - Nah, they wouldn't do that, would they?