Rats in Washington, DC? The Seoul of the Issue
By Stan Deresinski, MD, FACP, FIDSA
Clinical Professor of Medicine, Stanford University
SYNOPSIS: The Centers for Disease Control and Prevention has reported cases of the Seoul hantavirus in Washington, DC.
SOURCE: Ravi-Caldwell N, Iyengar P, Davies-Cole J. Notes from the field: First reports of locally transmitted Seoul hantavirus infection — District of Columbia, May 2018–December 2018. MMWR Morb Mortal Wkly Rep 2022;71:359-360.
The Centers for Disease Control and Prevention (CDC) reports two cases of infection caused by the Seoul hantavirus that were acquired in Washington, DC. The first was a previously healthy 30-year-old man who presented with a severe febrile illness with headache, sore throat, vomiting, and diarrhea over the previous four days. He became progressively more ill with the development of hemoconcentration, thrombocytopenia, and acute kidney injury. He then went on to develop hemophagocytic lymphohistiocytosis (HLH). Extensive microbiological evaluation was unrevealing, but testing for hantavirus infection was performed by CDC and was requested because the patient frequently had noted the presence of rodents during his activities as a maintenance worker. Antibody testing of serum found that both immunoglobulin G (IgG) and immunoglobulin M (IgM) titers against Seoul virus antigen were > 1:6,400, although virus isolation was unsuccessful. Supportive care was provided, and the patient was discharged after improvement. This case has been reported previously in greater detail.1
A 37-year-old man with chronic kidney disease presented with a three-day illness consisting of high fever and chills, headache, myalgia, and cough and with further development of vomiting and diarrhea. Hepatic transaminases were modestly elevated, he was thrombocytopenic, and his serum creatinine was 7.6 mg/dL. The patient, who was a dishwasher and plumber’s assistant, had no travel history, had no animal exposure, and had not noticed rodents in his environment. With suspicion of hemorrhagic fever-renal syndrome (the patient had presented five months after the first case), serum was tested at CDC and found to have IgG and IgM antibody to Seoul virus antigen at titers > 1:6,400. Testing for other etiologies was negative. The patient subsequently improved and was discharged from the hospital.
Hantaviruses are enveloped ribonucleic acid (RNA) viruses within the Bunyaviridae family, but, in contrast to other members of that family such as La Crosse virus, Rift Valley fever virus, and Congo-Crimean hemorrhagic fever virus, they are transmitted primarily by rodents via droplets rather than by arthropod vectors.2 At least 28 hantaviruses cause human disease, and these generally are categorized as New-World and Old-World hantaviruses. The former cause the hantavirus cardiopulmonary syndrome (HCPS), while the latter cause the hemorrhagic fever with renal failure syndrome (HFRS), although it is increasingly recognized that these syndromes may overlap.3
HCPS, caused by what came to be called the Sin Nombre virus, was first identified in the United States in 1993 as the cause of an outbreak in the Four Corners region of the Southwest and, as of December 2019, 816 cases of hantavirus infection causing HCPS had been identified in the country.2
In contrast, HFRS has been identified very rarely in the United States. Among the causes of HFRS is the Seoul hantavirus, which was the etiology of a 2017 multistate outbreak involving pet rat breeders and owners and affected 31 “ratteries.”4 Of the 17 human infections, seven were symptomatic and three required hospitalization. The reservoir for the Seoul hantavirus in the United States is the Norway rat, and previous sporadic cases had been linked to wild or pet rodents.
The initial symptoms of HFRS are fever with abrupt onset, chills, headache, and backache, as well as nausea and vomiting. Leukocytosis is present, and thrombocytopenia may evolve, often after three to seven days, at which time oliguria begins. Hypotension is common. Hemoconcentration is a consequence of widespread capillary leak. The occurrence of HLH, as reported in the first case described by the CDC, is exceedingly rare. Although the evidence for its efficacy is not robust, treatment with ribavirin often is recommended.
- Shastri B, Kofman A, Hennenfent A, et al. Domestically acquired Seoul virus causing hemophagocytic lymphohistiocytosis-Washington, DC, 2018. Open Forum Infect Dis 2019;6:ofz404.
- Centers for Disease Control and Prevention. Hantavirus infection in the United States. Page last reviewed Nov. 16, 2021.
- Avšič-Županc T, Saksida A, Korva M. Hantavirus infections. Clin Microbiol Infect 2019;21S:e6-e16.
- Kerins JL, Koske SE, Kazmierczak J, et al; Seoul Virus Working Group; Canadian Seoul Virus Investigation Group (Federal); Canadian Seoul Virus Investigation Group (Provincial). Outbreak of Seoul virus among rats and rat owners — United States and Canada, 2017. Can Commun Dis Rep 2018;44:71-74.
The Centers for Disease Control and Prevention has reported cases of the Seoul hantavirus in Washington, DC.
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