A dog in Chicago tested positive for rabies, marking the first case in Illinois in over 30 years. 

The Cook County Department of Animal and Rabies Control confirmed this is the first such case in Illinois since 1994, and the first in Cook County since before 1964.

The puppy in question was a rescue from Georgia, brought to the PAWS Chicago animal shelter in May. PAWS officials said the dog received all necessary vaccinations, including the Rabies vaccine, in June.

A family adopted the dog in July, but brought it back to PAWS last week after a bite in the home, along with behavioral changes.

The dog was humanely euthanized following a risk assessment by veterinarians and animal behavior specialists, and clinical tests by Cook County later confirmed the dog had rabies.

PAWS said, in the 27 years it has been operating, it has never seen this situation before out of more than 91,000 adoptions.

Dr. Claire Behnke, a veterinarian at Animal Medical Center of Chicago, said neither she nor any of her colleagues have ever seen a case of rabies in a dog before.

"This is luckily a very rare thing," Behnke said. "It's pretty scary. If you get infected with rabies and show signs of disease, it's like 99.9% fatal."

No one at Bow Wow Lounge doggy daycare has seen it before either.

"My initial first thought was, oh my gosh, this can't be possibly true, because of the vaccine, and because it's so rare," said Dr. Rory Lubold, with Destination Pet, which owns Bow Wow Lounge.

Lubold said the puppy that later tested positive for rabies was at the facility on four days this month.

"Everybody who was in the facility on those days has already been contacted," he said. 

Cook County officials said 13 people had direct contact with the dog during the possible contagion period and have started treatment. No one exposed has reported symptoms.

Rabies spreads from an infected animal to people through the saliva, most commonly through a bite from an infected animal, according to Cook County officials. Rabies can also spread when a rabid animal's saliva enters an open wound or the eyes, nose or mouth.  

"We don't know how the puppy got rabies," Behnke said.    

The Chicago Department of Public Health is investigating how a vaccinated dog contracted rabies. PAWS said the U.S. Centers for Disease Control and Prevention are testing the virus strain to help determine the origin of the dog's rabies infection.