M. bovis Infection in Wyoming Pronghorn
Livestock producers are familiar with the devastation that can be caused by Mycoplasma bovis (M. bovis) bacterium when it causes respiratory disease outbreaks in cattle herds. Stress on a herd (like at weaning time for calves, long transportation, bad weather, etc.) can trigger an outbreak of bovine respiratory disease complex, with treatment difficult. The bacterium is known to cause pneumonia, mastitis, arthritis, and abortion in cattle.
Until fairly recently, detection of M. bovis outbreaks were restricted to cattle; long a problem in dairy herds in the United States, the bacterium seems to have shifted in the last two decades to beef herds. In addition, an outbreak in 2006-2007 in a Kansas bison herd resulted in the deaths of 53 bison from the total herd of 194. Free-ranging ruminant cases are rare, although there have been a few cases reported in deer.
A new paper published in Emerging Infectious Diseases describes an outbreak detected in a herd of pronghorn antelope in early 2019 northeast of Gillette, Wyoming. In February that year, Wyoming Game & Fish Department responded to reports of about 30 dead pronghorn. The next month, another herd of 10 pronghorn moved into the same area (about 8 square-miles in size) and began dying, with landowners reported that affected pronghorn appeared lethargic. The animals were usually dead within 24 hours. At least 60 antelope with signs of respiratory disease died in the area during February through April. There were no reported outbreaks in area cattle, bison, or other ungulates during this outbreak, and no further cases were detected in Wyoming pronghorn.
In detecting M. bovis in a Wyoming pronghorn herd for the first time, the researchers also discovered a M. bovis genetic variation that supports the hypotheses that M. bovis might be expanding in host range and disease expression.