For anyone who has ever had a teddy bear, the idea of the same thing, only with a real bear can sound great. But scientists in California are concerned about a new disease that causes black bears in the state to behave “like dogs” with humans. They warn people not to get close to bears – no matter how friendly they look – because not much is known about the disease yet.
The California Department of Fish and Wildlife (CDFW) first noted the disturbing behavior in 2014. They were warned by colleagues from the Nevada Department of Wildlife, who have a number of encounters around Lake Tahoe’s pool with young bears that appear to have neurological problems.
After further research, the researchers found that bears have encephalitis – inflammation of the brain. Subsequent research also revealed five unprecedented viruses in sick animals – but it is unclear whether the viruses are the main cause of encephalitis.
Usually bears shrink around people and avoid us unless they are trying to get food. But sick bears look friendly and fearless.
Eventually, their illness leads to lethargy, severe weight loss, marked neck curvature, tremors, and abnormal gait.
In 2019, such a bear gained popularity on social media after someone photographed it in the ski resort Nortsar.
Most recently, in February 2021 in Pollock Pines, California, another sick bear was spotted wandering in a residential property. She looks lethargic and doesn’t seem to be afraid of the people she meets. Locals, who are increasingly attached to the bear, start feeding it strawberries and apples and giving it water – actions against the advice of the CDFW. At one point, the bear even climbs into the trunk of someone’s car and lets people pet it.
The CDFW does not encourage this type of interaction with wildlife such as bears. “At this point, we don’t know what causes their encephalitis,” said veterinarian Brandon Munk. “So we don’t know what, if any, health risks these bears can pose to other animals, including us.”
The Pollock Pines bear was picked up by CDFW staff. They notice that she is too young to walk alone. Physically and mentally, the animal “just doesn’t look quite right, walks strangely and doesn’t react like a normal bear should.”
After the bear was returned to the CDFW wildlife laboratory, further research showed that it was covered in ticks and weighed only 10 kilograms – a healthy bear its age should weigh about 35 kilograms. Veterinarians also observed periodic tilting and shaking of the bear’s head, signs of neurological damage.
Preliminary findings from the CDFW show that the young animal suffers from encephalitis – just like the others the agency notices. Overall, she is the third bear with neurological disorders due to encephalitis that the CDFW laboratory has accepted in the last 12 months.
“Every time a wild animal comes in, the best possible result is to put it back in the wild,” Munk said. “It’s just not possible for these neurological bears.”
However, the Pollock Pines bear must be euthanized. But Monk says that’s the best way out for her.
“The few bears like the one we picked up here don’t seem to be fully recovered,” he explains. They often require extensive and long-term medical care. “So neither putting them back in the wild nor keeping them here is a good option for them.”
For now, scientists are still trying to understand the root cause of the mysterious and disturbing disease. The researchers found that the five hitherto unknown viruses affected the liver and spleen, as well as the brain. In some ways, the disease is similar to the chronic debilitating disease seen in deer and elk. Like bears with encephalitis, animals with this condition develop symptoms that include weight loss, apathy, salivation, lack of fear, and eventually death.
Diseases are known to spread from animals to humans – probably with the coronavirus pandemic. But at least one scientist who has studied bear diseases believes that the mysterious disease will not pose a threat to humans. However, since not much is known about the disease, scientists recommend that people be careful.
