KNOXVILLE, Tenn. (WATE) — A second bear cub has died at Appalachian Bear Rescue due to an illness.

“Burrito Bear” passed away overnight on Oct.10. The curators and Executive Director, Dana Dodd, are talking with the doctors at the University of Tennessee College of Veterinary Medicine about what to do next.

Burrito’s body is being taken to UTCVM for necropsy. Tamale, Burrito’s brother, is also very sick and the doctors are planning to examine him at ABR.

“Whatever has infected our little bears is deadly and merciless. We hope to find out what it is so we can fight back,” wrote ABR on Facebook.

On Sunday, ABR shared that “Flapjack” the bear died at their facility from what appeared to be a severe case of pneumonia in both of his lungs. The rescue does not know what caused Flapjack to get so sick so quickly. The cubs that shared the enclosure with Flapjack were all taken to UTCVM for examination. At that time, ABR said that Tamale was in the worst shape.

“Most of the cubs have lesions in their throat that resemble strep throat, though the bacteria may not be strep,” wrote ABR on Facebook.

The vets are working to figure out the exact bacteria causing the illness.

The vets are doing cultures, but they don’t yet know the exact bacteria yet. They also do not know if the bacterial infection is primary or if it is secondary to a viral or parasitic infection. The other cubs are being given medicine and being watched carefully.

“We’ve never encountered anything like this in the 27 years of ABR’s existence. We’ve had single sick cubs arrive, but to have an infection spread so quickly through a group of healthy cubs is the stuff of nightmares. We owe it to Flapjack and all the cubs who will come after him to find out what happened and how to avoid it happening again,” wrote ABR.

ABR shares daily updates about the bears in their care on their Facebook page. Click here to learn more about the organization and how you can support their cause.