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Animal Health

Brucellosis reactors found, more tests pending

Written by Jennifer Womack
Cheyenne – The Wyoming State Veterinary Laboratory (WSVL) notified the Wyoming State Veterinarian June 10 that blood taken from two cows has reacted to diagnostic tests for brucellosis. The cows both came from a single herd near Daniel and were detected at one of the state’s livestock auctions.
    “Reactions on blood tests do not necessarily prove that cattle are infected with brucellosis,” says a June 12 press release from the Wyoming Livestock Board (WLSB). “However, these reactions were quite strong; this suggests that these cattle may well be infected. The two cows have been purchased by USDA/Animal Plant Health Inspection Service (APHIS) and sent to the WSVL for a full diagnostic evaluation.”
    Wyoming State Veterinarian Walt Cook told the Roundup June 12 that’s he very confident the cases are true brucellosis.
    According to the WLSB statement, “Tissues from the cattle will be cultured in an attempt to isolate the organism causing the reaction; it may take two weeks or longer to get final culture results. In the meantime, the WLSB is working with APHIS and the producer to complete blood tests on the remainder of the herd and may test neighboring herds as well.  The producer has been cooperative.”
    Depending on the outcome of additional testing on the source herd, which the agency is trying to do as soon as possible, neighboring herds could be tested according to Cook. “Yes, I think so,” said Cook when asked if the producers runs in a common allotment, “although I’m confused if he has breeding cattle that run in common with others.” Fortunately Cook said the approximately 300 head of cattle from the source herd haven’t yet been turned out to summer pasture. If test results from that herd warrant testing of neighboring herds, he said some cattle might have to be gathered off summer range. “That’s not a decision I look forward to making,” he said. There’s a chance additional testing won’t be done until fall.
    “We haven’t determined the source,” said Cook. “People jump to the conclusion that it’s wildlife, but he runs some cattle in with others and has fenceline contact with others.”
    Even if brucellosis infection is confirmed, these results will not automatically cause Wyoming to lose its “Brucellosis-Free” status granted by APHIS, provided no additional infected herds are identified. Maintaining the state’s brucellosis-free status may also require the herd to be depopulated. The state will need to go two more years without an additional case to maintain free status.  
    Brucellosis is a bacterial disease that can cause cattle, elk and bison to abort their calves and is a serious human health disease. A meeting with producers is scheduled for June 17 from 7-9 p.m. at the Pinedale Library.
    Jennifer Womack is editor of the Wyoming Livestock Roundup and can be reached at This email address is being protected from spambots. You need JavaScript enabled to view it..