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A mysterious neurological disease in young Californian black bears (American bear) forces them to behave like companion dogs, to get close to humans in a friendly way.
Although it looks cute, this anomalous behavior dramatically worsens the chances of bears surviving in the wild.
the bear, who are all around 1 year old, appear to be suffering from some form of infectious encephalitis – inflammation of brain tissue that can be caused by virus, bacteria, mushrooms and parasites, as well as as part of an autoimmune response. But vets aren’t sure exactly what’s causing the problem or how quickly it is spreading through the population.
Symptoms include a severe tilt of the head, lethargic movements, muscle tremors, seizures, walking in circles, and significant underweight, as well as surprising fearlessness towards humans.
Related: The 10 weirdest medical cases from the animal kingdom
“Infected bears come to our attention because they approach people in a peaceful, friendly and non-aggressive manner,” said Ann Bryant, executive director of the Bear Education Aversion Response (BEAR) League who has been involved in rescuing bears. infected. “Their behavior is similar to that of a dog, not a bear.”
In the past year, four people have been found to have the disease – the highest number of cases since it was first detected in 2014, according to the California Department of Fish and Wildlife (CDFW).
The black bear population in California has grown from 10,000 to 15,000 individuals in 1982 to 30,000 to 40,000 today, according to the CDFW. As a result, veterinarians are not too worried about the impacts of the disease on the general population.
Intrepid young people
Although cases of encephalitis are rare, the symptoms made it quite easy to spot infected bears.
“The first bear I personally saved was diagnosed with encephalitis in March 2018,” Bryant told Live Science. “She walked into a school and walked into a classroom where she sat among the children, behaving like a friendly dog.”
In 2019, another infected bear was filmed on video trying to get on a snowboard alongside his rider. The young man was eventually rescued after the snowboarder and his friends played with him and gave him sandwiches. However, friendly behavior does not mean that it is safe for humans to be around bears.
“Bears approaching people who could then treat the animal as if they were tame could easily pose a danger,” said Bryant. “I wouldn’t be comfortable with a member of the public trying to handle any of these bears, or any,”.
Instead, if anyone encounters bears showing symptoms of encephalitis, they should report it to the CDFW, Bryant said.
These two bears in particular are now residing in rescue centers, where they must receive constant medical attention to control the brain inflammation, but most other bears are not so fortunate.
The most recent bear with the disease, which was discovered in February lying in the back of a truck parked on a residential property, was grossly underweight and covered in fleas, and had to be shot due to its poor condition. physical condition. according to the bee of Sacramento.
Unfortunately, this sad fate has happened to the majority of infected bears, who are unable to take care of themselves and appear to have been abandoned by their mothers.
Increasing?
Veterinarians from the Nevada Department of Wildlife (NDOW) first discovered encephalitis in bears around Lake Tahoe on the California border in 2014, according to the CDFW.
Since then, the CDFW has recorded eight cases in California, although the actual number may be higher. Half of the confirmed cases were detected last year, but that doesn’t necessarily mean they are on the increase.
“My opinion is that it’s not increasing,” said Bryant. “But more studies are finally underway to make us more aware of this.”
The disease also does not appear to be transmissible between individual bears, said Bryant. This is encouraging for the rest of the population, but has left researchers perplexed as to the cause.
“The worst part about this threat to our bears is that we don’t know for sure what is causing it,” said Bryant. “The unknown is disturbing.”
Unknown origin
Infected bears are taken to the CDFW’s Wildlife Laboratory, where they can be treated or, more likely, euthanized due to their poor physical condition.
“Bears that die or are euthanized are autopsied to determine the cause of death,” Brandon Munk, senior wildlife veterinarian at the CDFW’s Wildlife Investigations Laboratory, told Live Science. “Tissue assessment can confirm whether an animal has had encephalitis or not.”
Although vets can identify the disease, determining the cause of encephalitis has proven to be much more difficult.
“Brain inflammation is probably what is causing the symptoms,” Munk said. “Beyond that, we don’t know the specific mechanics that may be in play.”
Potential pathogens have been identified as the cause of encephalitis, but none have been confirmed to date.
“We have identified five new black bear viruses, some of which are being pursued as possible causes of encephalitis,” Munk said. “We are also working with a research lab to further assess whether a protozoan parasite could be the cause.”
However, it’s also possible that there is more than one pathogen responsible for encephalitis, Munk said.
Originally posted on Live Science.
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