State veterinarian reviews brucellosis cases
Casper – Wyoming State Veterinarian Jim Logan spoke at the Wyoming Stock Growers Association (WSGA) livestock health and production committee meeting on Dec. 1 during the WSGA Winter Roundup in Casper, reporting on livestock health in Wyoming.
Brucellosis was addressed immediately, as one case has been confirmed in Park County recently. A positive test was confirmed in one cow in one herd of approximately 500 head. There was also one contact herd affected.
“The contact herd, by rule, is quarantined and required to test one time on all adult females. That has been done, and all of those cattle were negative, so the quarantine on the contact herd will likely, very soon, be released,” noted Logan.
The herd with the affected cow remains under quarantine and must undergo three consecutive, negative, total-herd tests at least 60 days apart. One of those tests must also be completed within 75 days of calving.
“We have to get a post-calving test because that is when antigens will be most likely to be in the blood stream of the cow for the test. If we are going to find the disease in an affected herd, it’s really critical that we do a post-calving test,” he explained.
Because of the seasonal timing that the brucellosis case was discovered, Logan is hopeful that the herd will meet all criteria to be released from quarantine before turnout next spring.
Logan also noted that finding only a single positive cow in a herd of nearly 500 head is a promising sign. Negative brucellosis tests within the herd and in the contact herd indicate that surveillance efforts are helping prevent the spread of the disease.
Another case of brucellosis has been detected in Sublette County, and the state vet lab released culture results testing positive for brucellosis on Dec. 10.
Five cows out of 62 head originally tested positive during a change of ownership test, required by Chapter Two Brucellosis Rules, and the herd was quarantined on Nov. 19, pending further results. As of Dec. 9, the herd has been designated as “brucellosis affected.”
Logan expressed his appreciation for cooperation from producers and veterinarians and added, “We expect to complete the initial stages of this response by the end of December with follow-up testing to occur in the following months.”
Five contact herds are currently under quarantine until further testing can take place to verify the absence of brucellosis in those animals.
“The Sublette County herd runs in common with about seven other producers, so we have seven contact herds. Luckily, if there is such a word in this context, three of those herds are not going to have to be tested because two of them run steers or spayed heifers. If we have neutered animals, we’re not worried about the spread of the disease,” Logan explained.
Some of the contact herds have already tested negative for brucellosis and additional animals are currently being evaluated.
“As far as we know right now, and logic would tell us this, it’s most likely that elk are the source of this brucellosis. The epidemiology done so far on all of these herds does not indicate there was any purchase of cattle coming in that would have brought the disease with them,” he commented.
Both cases were discovered within the boundaries of the designated surveillance area (DSA). Outside the DSA, seven seropositive elk have been detected over the last three years through hunter surveillance.
“When that first couple of elk were found in 2013 from the 2012 hunt season, it represented the first time that brucellosis had been found in anything, cattle or elk, outside of Wyoming’s DSA since Wyoming went brucellosis class free in 1985,” he mentioned.
This year, hunter-killed elk will continue to be monitored through mid-December, but so far, there have been no seropositive elk detected outside the DSA. Approximately 500 animals have been tested.
“We do have to be vigilant,” Logan stated. “If producers from Sheridan or Big Horn counties haven’t had risk assessments or don’t have herd plans, I would be happy to talk to them. A lot of people have stepped up, and we really appreciate that, but I think that there is more surveillance needed.”
That surveillance, he argued, is not just to satisfy other states but also to satisfy the cattle industry in Wyoming with assurance that there isn’t a barn door left open that a brucellosis affected cow can walk out of.
Natasha Wheeler is editor of the Wyoming Livestock Roundup and can be contacted at firstname.lastname@example.org.