THURSDAY, Oct. 31, 2024 (HealthDay News) -- When a black cat named Pepper dropped a dead mouse on the carpet at his owner's feet on a day back in May 2021, neither of them knew then that it would alert scientists to the arrival of an exotic virus to the United States. Pepper is a skilled hunter who regularly leaves “gifts” for his humans, so that part wasn't surprising.

But owner John Lednicky , a microbiologist with the University of Florida (UF) in Gainesville, did suspect the mouse might be carrying a virus called deer mulepox . Instead, lab tests showed the mouse was harboring the first jeilongvirus to be discovered in the United States, researchers reported recently in the journal Pathogens . Worse, it was a genetically mutated form of jeilongvirus, a type of virus previously detected in Africa, Asia, Europe and South America, Lednicky said.

“It grows equally well in rodent, human and nonhuman primate [monkey] cells, making it a great candidate for a spillover event” that could lead to a human epidemic or pandemic, Lednicky said in a university news release. Jeilingoviruses infect mammals, reptiles, birds and fish, and can occasionally cause serious illness in humans, Lednicky explained. They are a type of paramyxovirus, which are associated with respiratory infections.

“We were not anticipating a virus of this sort, and the discovery reflects the realization that many viruses that we don’t know about circulate in animals that live in close proximity to human.