The ongoing investigation by federal animal health agents into cases of brucellosis in Montana cattle represents a serious economic threat to the state's livestock industry, but it hardly comes as a surprise.

Not with the proximity of brucellosis-laden Yellowstone National Park right next door.

At this point it would be premature to get too alarmed, but testing being done on at two herds in the Paradise Valley is worrisome, because it only takes two infected herds to kick Montana from the list of brucellosis-free states. That would mean a huge, costly testing effort to regain that

status.

It also is too early to put the blame on Yellowstone bison. Elk or other cattle still can't be ruled out. But at least one rancher with a herd being tested -- and who stands to lose nearly 500 cattle -- said bison are by far the most likely culprit.

Opponents to the hazing of bison back into the park in recent years have pointed out that while bison have infected cattle in a controlled setting, there's no evidence of them doing so in the wild. Unfortunately, the current investigation just might provide that evidence.

There's no shortage of irony here. After all, the great reservoir of brucellosis in Yellowstone bison and elk came from early ranchers' cattle in the first place. But Montanans -- and Montana stockgrowers especially -- have every right to wish the problem could be dealt with more quickly.