A Mule Deer In Idaho Was Found Blind And Malnourished Due To A Rare Case Of Plague, Marking The First Documented Instance In The State
A rare case of plague has been confirmed in Idaho, where a mule deer was found to be blind and malnourished.
The plague is caused by the bacterium Yersinia pestis. Cases of plague occur naturally in parts of the western United States among wild rodents and other animals.
Previously, there have been five documented cases of plague in deer, and none of them were in Idaho.
The disease causes deer to develop lesions in the eyes, resulting in blindness. The condition has been referred to as ocular plague.
“Deer and other ruminants don’t appear to be particularly susceptible to plague, but in the few published cases, it has specifically been found in the eyes,” said Elis Fisk, a pathology resident at Washington State University.
“The disease doesn’t necessarily kill the deer on its own, but it causes blindness, likely making them vulnerable to predators and significantly reducing their chances of survival.”
For humans, exposure to plague can lead to serious illness and death if antibiotic treatment is not started early.
Wildlife officials recommend staying away from any animal that is blind or displaying strange behavior and reporting the location and species of animal to their state wildlife agency.
A member of the public reported the deer in Custer County. An officer from the Idaho Department of Fish and Game euthanized the animal.
Matthew – stock.adobe.com – illustrative purposes only, not the actual deer
Samples from the deer were extracted and sent to the Washington Animal Disease Diagnostic Laboratory (WADDL) for testing.
“When we received the samples, the eyes appeared highly abnormal,” Fisk said. “Usually, when you cut into the eye, it contains clear fluid, but in this case, it was filled with thick, reddish-brown debris. The other interesting thing was the retina was detached, and there was significant inflammation and necrosis.”
Plague is incredibly rare, but the deer’s symptoms were similar to cases seen in Wyoming and Oregon, so the researchers decided to test for plague to rule it out.
They used a polymerase chain reaction test to analyze small amounts of DNA. It confirmed the deer suffered from the plague.
The plague was only detected in the deer’s eye samples, not in any organs or tissues. It is unclear why that is, but the researchers suspected that the bacteria from the plague may have already cleared from the other tissues by the time the samples were gathered and examined.
It is a challenge to determine how prevalent ocular plague in deer is because infected animals will likely die from natural causes or fall prey to predators before humans run into them.
“It’s probably just a super rare finding that anyone came across this animal before it died in the wild,” said Dr. Kyle Taylor, a pathologist at WADDL.
After testing, the samples were destroyed for safety purposes, and the case was reported to the Centers for Disease Control and Prevention.
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