I've been thinking more about this and think that Hazel's idea is a good one, I know they were testing dead Crows and Blue-jays for West Nile, although I think that this year they stopped because there were just too many.
One thing I have noticed at my feeders is that for the past week, maybe more, I haven't seen one Blue-jay, normally they are flying in and out all day long. I looked on the ground along the tree line between our property and the neighbours, which is heavily treed and full of birds, but nothing....something is going on and I don't like it one iota...........I'm scratching my head on this one