CDC and health officials from Wisconsin and Illinois are conducting an investigation of Seoul virus infections among pet rats and persons exposed to rats at rat-breeding facilities in Wisconsin and Illinois. Seoul virus is a member of the hantavirus group of rodent-borne viruses. Trace-back and trace-out investigations of possibly infected rodents have identified distribution chains in other states that may require additional investigations. People who become infected with this virus often exhibit relatively mild or no symptoms, but some will develop a form of hemorrhagic fever with renal syndrome (HFRS) with death in approximately 1–2% of HFRS cases. Although serologic studies have indicated the presence of Seoul virus in wild rats in the United States, this is the first known outbreak associated with pet rats in the United States.
• As part of the outbreak investigation, CDC and Illinois and Wisconsin health officials are conducting trace-back and trace-out investigations to determine where rodents from confirmed positive facilities may have been distributed.
• CDC currently recommends testing of all persons who report recent or current illness after (1) handling rats from a facility with Seoul virus infection that was confirmed by laboratory testing (either rat or human), or (2) handling rats from a facility that sold rats to a facility with Seoul virus infection. Testing is also offered to persons without illness but (1) who are reporting exposure to rats from a facility with Seoul virus infection that was confirmed by laboratory testing, or (2) who are reporting exposure to rats from a facility that sold rats to a facility with Seoul virus infection but where no illness has been reported.
• In general, CDC recommends consideration of hantavirus testing in all persons with symptoms of Seoul virus infection and rat contact, even if the rat was not associated with a facility where a confirmed infection in a rat or human was reported.
• In the United States, hantavirus infections in people are notifiable conditions. Healthcare providers who suspect hantavirus infection in a patient should contact their state or local health department.
Read the full advisory here (PDF file).