Nancy, I don't know anything except for inappetence/lethargy/kidney failure/death. I don't know any of the owners but for one dog and I didn't ask questions when I ran into the husband yesterday morning.
I have no idea of how long things ran except "fast".
That's it other than the visit to this one particular park...either regularly (the dog I knew) or regular/sporadically (the others). And that could, obviously, be a coincidence. I do know they spray stuff in that park and the yellow signs aren't always where people would see them, depending on the direction they're coming from...and they're not put in all the areas. (Like: OK, we sprayed in the park today...just avoid everywhere.) And we have a lot of wildlife in the area and I've been told that we have Lepto.
I don't know what vets were visited (except one to what I presume is the local emergency vet and not the one about 10 miles away) and I have no idea what the vets tested for.
That's why I'm eager to hear from my vet or perhaps learn something more from anyone who posts more info on our local forum. I'm hoping I don't see more dogs added to the list of those who've succumbed.