The infected animal had been vaccinated.
This has been a perennial issue in areas surrounding the elk feedlots in Wyoming. It now seems that brucellosis has once again infected cattle in Idaho but it is too early to say where the disease originated. If brucellosis is found in another cattle herd in Idaho within a year then Idaho, once again, will lose its brucellosis free status and all cattle that are exported will have to be tested for the disease.
For years this scenario was held over the heads of people who support free roaming bison in Montana yet, when it came to pass, it turned out to be more of a minor inconvenience rather than the catastrophe the livestock industry claimed it would be.
This issue has been used rather effectively against wildlife for years but the disease is much less of a threat to human health than it was before the pasteurization of milk became the standard. The only way to contract brucellosis is by coming into direct contact with infected fetal tissue or by drinking unpasteurized milk. You cannot become infected by eating cooked beef.
Livestock disease found in eastern Idaho cow
By REBECCA BOONE (AP)