Authorities are warning the public after an outbreak of a rat virus that has been linked to ratteries in Illinois and Wisconsin, and public health officials are working to get a handle on the problem. The virus is rarely seen in the United States, but it recently infected eight people in the two states who worked in facilities that bred pet rats.

It all started when two people in Wisconsin who worked in a rat-breeding facility became ill in December, forcing the hospitalization of one of them. The breeders tested positive for what is known as the Seoul virus, which is part of a group of viruses found in rodents. Later, health officials discovered that six people who worked at facilities in Illinois were infected with the same virus.

The virus infects a rat species called the Norway or brown rat, which is found worldwide. It’s possible for people to catch the virus from rats, but it’s rare and almost always happen in Asia. This is the first time the Seoul virus has been linked to pet rats in the U.S.

“Seoul virus is not known to be transmitted from person to person. Therefore, the general public is at extremely low risk,” said IDPH Director Nirav D. Shah, M.D., J.D. “Out of an abundance of caution, we want to let the public know in the event they have recently purchased rats from an affected facility and become ill.”