The Montana Department of Livestock (DOL) announced on Tuesday that brucellosis was confirmed in an animal from a Gallatin County ranch within Montana’s Designated Surveillance Area.
According to a DOL news release, the infected animal had a negative test in 2021, but a voluntary herd test last month indicated the animal had been exposed to and infected by brucellosis. DOL quarantined the herd after the animal tested as a reactor, and the Montana Veterinary Diagnostic Laboratory collected tissues from the animal post-mortem.
The samples were sent to the National Veterinary Services Laboratories in Ames, Iowa; infection was confirmed by culture.
According to DOL, voluntary herd testing can reduce the impact of brucellosis—a bacterial disease that can infect humans, cattle, bison, and elk—on Montana livestock producers.
“A voluntary annual herd test can be performed at a time when animals are already being worked such as fall pregnancy checking,” State Veterinarian Marty Zaluski stated in the release. “The ability to control the timing of a herd test minimizes disruption when testing is required as part of an epidemiological investigation.”
“A robust testing program not only benefits individual operations but protects our entire industry and our trading partners,” he added.
Brucellosis can result in abortion or the birth of weak calves and is primarily transmitted through contact with infected birth tissues and fluids, according to the DOL release. Past cases in livestock were determined to be the result of transmission from infected wild elk. The source of brucellosis infection in the Gallatin County herd has not yet been determined.
DOL's release did not identify the type of brucellosis-infected animal or the location of the herd within Gallatin County. It is the 12th brucellosis-affected herd detected since the creation of Montana's Designated Surveillance Area in 2010.