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Seoul Virus

Seoul virus is an Old World hantavirus in the Bunyaviridae family. Its natural reservoir is the Norway rat (Rattus norvegicus). Rats infected with Seoul virus are asymptomatic, but can transmit the virus to humans through infectious saliva, urine, droppings, or aerosolization from contaminated bedding. Human signs and symptoms of infection range from mild influenza-like illness to hemorrhagic fever with renal syndrome (HFRS). HFRS causes acute renal failure that may be fatal. Asymptomatic Seoul virus infections also occur. Transmission from rats to humans is rare. Seoul virus is not known to spread from person to person.

A recent investigation by CDC identified the first known transmission of Seoul virus from pet rats to humans in the United States and Canada. Thirty one rat breeding facilities in 11 states had human or rat infections. Among 17 patients in the United States with recent Seoul virus infection, 8 reported recent febrile illness and 3 were hospitalized.

Human Seoul virus infections were laboratory-confirmed by detection of Seoul virus-specific IgM and/or IgG antibodies by enzyme-linked immunosorbent assay (ELISA). In the United States, Seoul virus infections in rats were confirmed through detection of viral RNA by reverse transcription–polymerase chain reaction (RT-PCR).

Human hantavirus infections are nationally notifiable in the United States and suspected cases should be reported to state or local health departments. Health care providers should consider Seoul virus infection in patients with febrile illness who report rat exposure; CDC recommends testing for any person with compatible illness and rodent contact.


Kerins JL, et al. Outbreak of Seoul Virus Among Rats and Rat Owners — United States and Canada, 2017. MMWR February 2, 2018; 67(4);131–134.

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Childs JE, Korch GW, Smith GA, Terry AD, Leduc JW. Geographical distribution and age related prevalence of antibody to Hantaan-like virus in rat populations of Baltimore, Maryland, USA. Am J Trop Med Hyg 1985;34:385–7.

Ksiazek TG, West CP, Rollin PE, Jahrling PB, Peters CJ. ELISA for the detection of antibodies to Ebola viruses. J Infect Dis 1999;179(Suppl 1):S192–8

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