"Hantavirus" is not one virus. It is a genus of more than 40 species sharing a rodent reservoir, but they differ on which rodent carries them, where they circulate, what organ they wreck, and how lethal they are. Sin Nombre in the American Southwest kills about a third of people it infects. Puumala in Finland kills less than 1 percent. Andes in Patagonia is the only hantavirus with sustained person-to-person transmission.
This post unpacks the major species so surveillance signals make sense when one appears on an event card. Rodent-exposure epidemiology is in hantavirus: the rodent-borne threat; how we weight events is in disease severity scoring. What follows is the species-by-species picture you need to read either correctly.
Key Takeaways
- Hantaviruses split into two syndromes: HPS (pulmonary) in the Americas, HFRS (hemorrhagic with renal) in Europe and Asia.
- Sin Nombre is the dominant US strain, carried by the deer mouse, with ~850 cases since 1993 and a 36 percent CFR per CDC.
- Andes virus in Argentina and Chile is the only hantavirus with well-documented person-to-person transmission (1996 El Bolson, 2018 Epuyen).
- Seoul virus is unusual because its Norway rat host lives almost everywhere humans do; a 2017 US outbreak among pet rat owners proved the point.
- Hantaan causes severe HFRS in Korea and China (5 to 15 percent CFR); Puumala causes a milder form in northern Europe (CFR under 1 percent).
- All hantaviruses spillover through inhaled rodent excreta. Only Andes spreads between humans.
How are hantaviruses classified?
Hantaviruses belong to the family Hantaviridae, order Bunyavirales. The genus Orthohantavirus contains the species that infect humans. Each species pairs with one or two rodent hosts, and the pairing is tight enough that virus phylogeny tracks rodent phylogeny across deep evolutionary time. Knowing the rodent predicts the virus.
Two clades matter. New World hantaviruses circulate in cricetid rodents (mice and rats of the Americas) and cause HPS. Old World hantaviruses circulate in murid rodents (rats and voles of Eurasia) and cause HFRS. Hantaviruses have also been found in shrews, moles, and bats, but the human relevance is unresolved.
| Virus | Reservoir | Geography | Syndrome | Case fatality |
|---|---|---|---|---|
| Sin Nombre | Deer mouse (Peromyscus maniculatus) | Western US, Canada | HPS | ~36% |
| Andes | Long-tailed pygmy rice rat (Oligoryzomys longicaudatus) | Argentina, Chile | HPS | ~25 to 35% |
| Seoul | Norway rat (Rattus norvegicus) | Worldwide | Mild HFRS | ~1 to 2% |
| Hantaan | Striped field mouse (Apodemus agrarius) | Korea, China, Russia | Severe HFRS | ~5 to 15% |
| Puumala | Bank vole (Myodes glareolus) | Northern Europe | Mild HFRS (NE) | <1% |
| Dobrava | Yellow-necked mouse (Apodemus flavicollis) | Balkans, Central Europe | Severe HFRS | ~10 to 12% |
What is Sin Nombre virus?
Sin Nombre virus (SNV) is the prototypical New World hantavirus and the dominant cause of HPS in the United States. It was identified during the 1993 Four Corners outbreak, when 24 people in Arizona, Colorado, New Mexico, and Utah developed acute respiratory failure and 13 died before the pathogen had a name. The reservoir is the deer mouse (Peromyscus maniculatus), one of the most abundant small mammals on the continent.
Through 2024, CDC surveillance has logged roughly 850 confirmed HPS cases in the US with a 36 percent case fatality rate. New Mexico, Colorado, Arizona, California, Washington, and Montana account for most. Cases concentrate where deer mice colonize cabins, sheds, barns, and outbuildings. The 2012 Yosemite tent-cabin cluster (10 cases, 3 deaths) is the most cited point-source outbreak.
SNV does not transmit between humans. Every confirmed US case traces back to inhaled aerosolized rodent excreta. Pandemic potential is essentially zero, but individual case lethality is high enough that any HPS cluster gets investigated aggressively.
What is Andes virus and why does it transmit person-to-person?
Andes virus (ANDV) is the South American counterpart to SNV and the only hantavirus with well-documented sustained human-to-human transmission. It circulates in the long-tailed pygmy rice rat (Oligoryzomys longicaudatus) across Patagonian Argentina and southern Chile. Clinical disease is HPS with a 25 to 35 percent case fatality rate. What sets ANDV apart is the documented transmission chains.
The 1996 El Bolson outbreak in Argentina was the first time epidemiologists could not explain a hantavirus cluster by shared rodent exposure. Cases included physicians treating index patients hundreds of kilometers from any plausible rodent source. Genomic sequencing later confirmed that patients carried the same ANDV variant in chains running three or four generations deep.
The 2018 to 2019 outbreak in Epuyen, Argentina, made the pattern unmistakable: 34 confirmed cases, 11 deaths, and a household attack rate no zoonotic-only model could explain. Argentine authorities quarantined the town. Person-to-person transmission of ANDV is now treated as an established feature, not a rare event. The mechanism is presumed respiratory droplet and short-range aerosol, though efficiency is low (R0 well under 1.0 in most settings).
What is Seoul virus?
Seoul virus (SEOV) is carried by Norway rats (Rattus norvegicus) and black rats (Rattus rattus), so its range tracks human shipping and urbanization rather than wilderness. Norway rats live almost everywhere people do: cities, ports, sewers, farmyards, and increasingly homes via pet rats.
Clinical disease is a milder form of HFRS. Acute kidney injury, fever, and headache are typical; case fatality runs 1 to 2 percent. Most infections in endemic settings are subclinical. Seoul virus is on this list for its geographic ubiquity and its capacity for surprise outbreaks in non-traditional settings.
The clearest recent example is the 2017 US and Canadian outbreak among pet rat owners and breeders. CDC traced 31 confirmed and probable cases across 11 states to ratteries selling fancy pet rats infected with SEOV. The cluster confirmed that imported pet rodents can carry hantavirus into homes with no other rodent exposure. Surveillance now treats commercial rat breeding as a credible exposure pathway in any unexplained HFRS-like illness.
What are Hantaan and Puumala viruses?
Hantaan virus (HTNV) is the Old World prototype, isolated by Ho Wang Lee in 1976 from striped field mice (Apodemus agrarius) near the Hantan River in Korea. It causes severe HFRS that has killed Korean and Chinese soldiers and farmers for at least a century. China alone records 20,000 to 50,000 HFRS cases per year, mostly Hantaan or Seoul. CFR for severe Hantaan disease runs 5 to 15 percent in modern hospital care.
Puumala virus (PUUV) is the northern European hantavirus, carried by the bank vole (Myodes glareolus). It causes nephropathia epidemica (NE), a mild form of HFRS. Finland, Sweden, and parts of Russia each see thousands of NE cases per year, with peaks tracking bank vole cycles. Case fatality is below 1 percent, but morbidity is real.
Dobrava virus (DOBV) sits between them: Balkan and Central European range, yellow-necked mouse reservoir, severe HFRS with a 10 to 12 percent CFR. Of the European species, Dobrava is closest in severity to Hantaan.
How does HPS differ from HFRS?
HPS and HFRS target different organs. HPS attacks the lungs, producing rapid pulmonary edema and respiratory failure. HFRS attacks the kidneys, producing hemorrhagic fever, vascular leak, and acute kidney injury. New World hantaviruses cause HPS; Old World hantaviruses cause HFRS. The split is clean enough to be diagnostic.
HPS runs in two phases. A 2 to 5 day prodrome of fever, myalgia, and headache (indistinguishable from flu) gives way abruptly to severe respiratory distress driven by capillary leak in the pulmonary microvasculature. Patients can go from walking-wounded to ventilator within hours. Survival depends on ICU support arriving before cardiopulmonary collapse. Detailed timeline is in hantavirus pulmonary syndrome symptoms.
HFRS runs through five phases: febrile, hypotensive, oliguric, polyuric, and convalescent. The middle three are when patients die, typically from shock or acute kidney failure. Severe HFRS (Hantaan, Dobrava) needs ICU care and sometimes dialysis. Mild HFRS (Puumala, Seoul) is usually managed on a regular ward.
Both syndromes share one mechanism: hantaviruses target endothelial cells in small blood vessels, and vascular leak drives the clinical picture. Why one virus prefers pulmonary endothelium and another prefers renal endothelium is unresolved. No specific antiviral has proven benefit for HPS. Ribavirin shows modest benefit for early Hantaan HFRS when started in the febrile phase.
FAQ
Are all hantaviruses equally dangerous?
No. Case fatality varies by more than two orders of magnitude. Sin Nombre and Andes kill 25 to 36 percent of confirmed patients. Hantaan and Dobrava run 5 to 15 percent. Seoul virus runs 1 to 2 percent. Puumala, the dominant European strain, kills less than 1 percent. Geographic location and species identification drive prognosis far more than any individual patient factor.
Can you catch hantavirus from another person?
For almost all species, no. Sin Nombre, Hantaan, Puumala, Seoul, and Dobrava viruses are not known to transmit between humans. Andes virus is the documented exception, with sustained person-to-person transmission confirmed in Argentine and Chilean outbreaks since 1996. If a hantavirus case appears outside Patagonia, treat it as zoonotic only until proven otherwise.
Why does Seoul virus appear in pet rat outbreaks?
Seoul virus circulates in Norway rats and can be carried asymptomatically by pet rats descended from wild populations. The 2017 US outbreak traced 31 cases across 11 states to ratteries selling SEOV-infected fancy rats. Pet rats shed the virus in urine, saliva, and droppings inside the home, and owners inhale aerosolized particles during cage cleaning. Routine veterinary screening would prevent most cases.
Is there a hantavirus vaccine?
For most species, no. South Korea and China have used inactivated whole-virus vaccines (Hantavax in Korea, two products in China) against Hantaan and Seoul viruses for decades, with reasonable but imperfect efficacy. No vaccine is licensed in the US, EU, or anywhere in the Americas. mRNA and DNA candidates against Sin Nombre and Andes viruses have advanced through preclinical work but none has reached licensure.
Should hantavirus be on a global pandemic watch list?
Hantaviruses are not pandemic pathogens in the SARS-CoV-2 sense. Even Andes virus has an effective reproduction number well below 1.0 in most documented chains. The pandemic concern is a future hantavirus, or a derivative of one, that combines HPS-level lethality with sustained human transmission. Surveillance for that scenario is one reason rodent ecology and outbreak genomics get continued investment.