Wyoming State Veterinarian Dr. Jim Logan has been notified that cultures are positive for field strain Brucella abortus (Brucellosis) on a cow from one Park County cattle herd. Results were received on November 19, 2015 from the Wyoming State Veterinary Laboratory (WSVL) in Laramie, Wyoming.

Cow and calf Image/Agricultural Research Services
Cow and calf
Image/Agricultural Research Services

Dr Logan, with concurrence of USDA-APHIS, has designated the herd from which the reactor cow originated as “Brucellosis affected” as of that date.

One cow that originated from a herd within Wyoming’s Designated Surveillance Area (DSA) was positive to blood tests at the WSVL and the National Veterinary Services Laboratory (NVSL) in Ames, Iowa. Specified cattle from the DSA are required to be tested within 30 days prior to change of ownership or movement from counties within the DSA. The herd was quarantined on November 10. It will remain under quarantine until the herd has undergone three consecutive, negative, whole-herd tests after any reactors have been removed from the herd.

Whole-herd testing was conducted on the “affected” herd on Nov. 15, and no additional reactor animals were identified. There is one contact herd also under quarantine for herd testing. The contact herd could be released from quarantine if their herd test is negative.

The testing is being conducted as a cooperative effort between herd owners, Wyoming Livestock Board (WLSB) personnel, and private veterinary practitioners. Epidemiologic interviews with herd owners are ongoing and quarantine herd plans will be developed with each herd owner associated with the case. Epidemiologic tracing will be conducted in the upcoming weeks by WLSB and APHIS personnel.

“Finding Brucellosis in our DSA is not an unexpected event,” said Logan. “We have a reservoir of Brucellosis in wildlife in northwest Wyoming that occasionally will spill over into cattle. Our producers do a good job of mitigating their risks and trying to prevent Brucellosis in their cattle herds. This situation illustrates the value and effectiveness of our surveillance program in Wyoming. We have found this case before the disease spread to other areas and are dealing with it appropriately. At this time, we do not have verification that this case has resulted from wildlife exposure. The epidemiological investigation will give us an answer with time. All of Wyoming’s cases of Brucellosis, from 2003 to 2011, have been verified as elk source exposure.”

Logan would like to thank all the producers and veterinarians in the area for their good cooperation in a very difficult situation. “We expect to complete the initial stages of this response by the end of November with follow-up testing to occur in the ensuing months.”

WLSB veterinary staff is also currently investigating a potential case of Brucellosis in Sublette County, which is also in the DSA. Blood test results indicate there may be a positive herd. Dr. Logan is waiting on tissue culture results from animals submitted to the WSVL before designating the herd officially. If this is an “affected herd,” there will likely be additional contact/exposed herds that will need to be quarantined until tested.