The Centers for Disease Control and Prevention (CDC) is working with health officials in 15 states regarding the investigation of an outbreak of Seoul virus infection, according to an update on the agency’s website.

Thus far, 11 people in Illinois, Indiana, and Wisconsin have had laboratory-confirmed infection after initial reports that 2 persons who operated a home-based rat-breeding facility in Wisconsin were hospitalized in December. The individuals had purchased rats from animal suppliers in Wisconsin and Illinois. Subsequent investigation into 2 ratteries in Illinois revealed an additional 6 individuals who tested positive for Seoul virus. All have recovered.

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Potentially infected rodents may have been distributed or received in Alabama, Arkansas, Colorado, Illinois, Indiana, Iowa, Louisiana, Michigan, Minnesota, Missouri, North Dakota, South Carolina, Tennessee, Utah, and Wisconsin.

Seoul virus is a type of hantavirus in which infected persons frequently exhibit relatively mild or no disease, although some will develop a form of hemorrhagic fever with renal syndrome, with death occurring in 1% to 2% of cases.

Symptoms of Seoul virus infection, which usually begin within 1 to 2 weeks after contact with infectious material, include the following:

  • Fever
  • Headache
  • Back and abdominal pain
  • Chills
  • Nausea
  • Blurred vision
  • Flushing of the face
  • Inflammation or redness of the eyes
  • Rash

Persons who handle the brown or Norway rat, the known carrier of Seoul virus, are advised to take precautions to minimize risk of infection, with special consideration given to the following:

  • Protection of bare skin and mucous membranes from contact with rodent excreta and nesting materials
  • Hand hygiene
  • Cleaning method for rodent housing environments and habitats
  • Choice and use of disinfectants
  • Decontamination of equipment
  • Proper disposal of waste


  1. Multi-state outbreak of Seoul virus. Centers for Disease Control and Prevention. Updated February 9, 2017. Accessed February 10, 2017.