Tennessee and ten other states are home to the first known cases of humans infected by a rat virus according to the Centers for Disease Control and Prevention (CDC). Officials say health departments in Tennessee and Wisconsin were able to trace back reports of an unspecified viral illness in patients dating back to December 2016. An 18-year-old Tennessee girl was found to have developed fever, chills, anorexia, nausea, and blood in her urine. She recovered a month later, but a follow-up found she became infected with what’s called Seoul virus from her pet rats. A few months later, the girl’s 38-year-old mother checked into the emergency room with similar symptoms, but doctors noted the woman’s fever was a scorching 104 degrees. The mom reported she could only recall one instance where she was exposed to rodent droppings, having cleaned some from a bathtub three weeks before symptoms arose.

Also in December 2016, a Wisconsin patient checked into the hospital with similar symptoms as the women in Tennessee, although this patient worked at an in-home rat breeding facility containing 100 Norway rats. Ultimately, the CDC traced multiple infections and transmissions back to 31 facilities in 11 states. Those states were Tennessee, Colorado, Georgia, Iowa, Illinois, Minnesota, Missouri, Pennsylvania, South Carolina, Utah, and Wisconsin.

Rats, (both wild and pets) can carry the virus which is passed to humans via a rat bite or by coming into contact with infected rodent saliva, urine, or droppings. The CDC says when fresh rodent urine or nesting materials are stirred up via vacuuming or sweeping, tiny particles containing the virus can become airborne. If inhaled, a human can become infected. Humans infected by the Seoul virus often exhibit mild or no disease, but some could develop a form of hemorrhagic fever with renal syndrome that can cause death in 1-2% of cases. Typical symptoms include fever, vomiting, headache, back or abdominal pain, blurred vision, rash, and inflammation or redness of the eyes.