The first patient in this cluster to die should provide confirmation of CJD or other prion disease.

There is a theory that spontaneous CJD can be spread environmentally. Apparently particles of sufficiently small size (10 nm) can pass from the nasal cavity directly into the brain via the olfactory nerve. And there was a cluster of CJD victims who were rose gardeners. Rose gardening commonly use Bone and Blood meal to feed the roses, and is typically made from cattle unfit for consumption-ie downer cows/BSE. I may have read about it in The Coming Plague: Newly Emerging Diseases in a World Out of Balance Book by Laurie Garrett.

They've done autopsies on 11 which pointed to various known conditions according to the article.