Here is the latest news as reported by the Bozeman Chronicle. By Scott McMillion. The infected cattle at Bridger, Montana, might have originated from near Emigrant (closer to Yellowstone Park, but still not an area where they would ever encounter bison).
[Governor] Schweitzer said last week that it doesn’t appear the infected herd ever commingled with bison from Yellowstone National Park, but [Montana Stockgrower’s spokesperson] Bodner said it’s too early to pinpoint the source of the disease. . . from the Chronicle.
350 cows are under quarantine. This includes 50 that had already been shipped to Iowa.
I suspect the origin will turn out to be Montana elk (which have a low, but non-existent incidence of brucellosis), or cattle shipped from Wyoming, which lost its brucellosis free status in 2005 due to infected elk from the Muddy Creek elk winter feedlot mingling with adjacent cattle.
Wyoming has since regained its brucellosis free status, but I suspect will lose it again due to the high elk infection incidence which perpetuated by winter feeding of elk.
Meanwhile Idaho held hearings on new rules so it can regain its brucellosis free status. I’ve seen no media on it yet, another indication that how serious or not this matter is thought to be depends on the activity level of political interest groups
Update. May 23. Brucellosis tests of cattle herds near Yellowstone come up negative (so far). By John Falstad. Billings Gazette.
It was suspected that the brucellosis at Bridger, Montana might have come from cattle purchased closer to Yellowstone Park — at Emigrant, Montana in Paradise Valley. Testing at the ranch at Emigrant showed no brucellosis. Other ranch herds are being tested.