It could have been a simple propagation test for some other worse mosquito-born disease, or it was an attack that to date has not worked as well as planned.
I know, call me a tinfoiler, but I flatly refuse to believe it was a random event.
IMO, if a link could be found and proven, the Government would have to face the reality of a justified nuclear response, which we had threatened Iraq with in the past. And no one at present wants to deal with that, so we shall sit here with our heads in the sand and pretend it did not happen. So a crow flew from some African pesthole, all the way to New York, or a mosquito stowed away on a plane, and promptly found a bird.
Sure, OK.