Cats are dying at an unusually high rate in a city northeast of Denver, enough so that authorities have cautioned the public about the situation.

According to the Brighton Police Department, local animal welfare services have noticed a high rate of sick or deceased cats in the Brighton East Farms neighborhood over recent days and weeks.

The cause of the uptick in cat deaths has not officially been determined, but it’s worth noting that feline panleukopenia virus has been detected among sick cats in the area.

As a result of the situation, residents who own cats have been instructed to stop letting their animals roam outside. Those who take care of stray cats have also been asked to remove any sort of shared bedding, litter boxes, or food sources, as these can be sites of cross-contamination and the spread of potentially dangerous health concerns.

According to the American Veterinary Medical Association, feline panleukopenia virus (FPV) can spread easily between cats when it pops up in a population, typically passed along via bodily fluids, feces, and fleas. In the modern era, however, severe cases tend to be uncommon thanks to effective vaccines that exist.

Young cats aged three to five months are often most at-risk of death from the virus. No medications exist that kill the virus, though some medical treatments can increase the likelihood of survival among infected cats. Without supportive care, up to 90 percent of FPV-positive cats can die.

Initial symptoms include lethargy, loss of appetite, a high fever, diarrhea, nasal discharge, vomiting, and dehydration. Mild cases tend to go unnoticed and can also help a cat develop immunity from future infection. Vaccination offers the best protection from the virus among cats that have not obtained natural immunity.