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Virus profile

Sin Nombre virus

SNV · Four Corners virus · HPS

Syndrome
HPS
Reservoir
Deer mouse
Region
North
CFR
approximately 36–38%
Reservoir & range

Rodent host: Deer mouse (Peromyscus maniculatus). Region: North America (especially the western and southwestern United States). First identified: 1993, in the Four Corners region of the United States.

Overview

Sin Nombre virus is the most clinically significant hantavirus in North America and the strain responsible for the original 1993 Four Corners outbreak that led to the recognition of hantavirus pulmonary syndrome (HPS). It is carried by the deer mouse (Peromyscus maniculatus), one of the most widely distributed rodents on the continent. Humans are infected almost exclusively by inhaling aerosolized particles from rodent urine, droppings, or saliva — typically while cleaning enclosed spaces with rodent activity (cabins, barns, sheds, crawl spaces). Person-to-person transmission has not been documented for SNV.

Tracked countries

Live risk index and news for countries where Sin Nombre virus is documented or surveilled.

United StatesCanadaMexico

Notable outbreaks

  1. 1993
    Four Corners region (NM/AZ/CO/UT)

    Initial cluster of unexplained respiratory illness among healthy young adults; led to identification of SNV and the HPS case definition.

  2. 2012
    Yosemite National Park, California

    Ten cases linked to deer-mouse contamination of double-walled tent cabins at Curry Village.

  3. 2024–2025
    California Eastern Sierra (Mono County)

    Multi-case cluster prompted state health-department warnings about deer-mouse exposure in rural and recreational settings.

FAQ

Sin Nombre virus: questions answered

What is Sin Nombre virus?
Sin Nombre virus is the principal hantavirus strain responsible for hantavirus pulmonary syndrome (HPS) in North America. It is carried by the deer mouse and was first identified during the 1993 Four Corners outbreak in the United States.
Where is Sin Nombre virus found?
Sin Nombre virus is documented across most of the contiguous United States and Canada. The highest cumulative HPS case counts come from the western and southwestern United States — New Mexico, Colorado, Arizona, California, Washington, and Montana — but cases have been reported in nearly every US state with deer-mouse populations.
How fatal is Sin Nombre virus infection?
Hantavirus pulmonary syndrome caused by Sin Nombre virus has a case-fatality rate of roughly 36–38% in the United States, making it among the most lethal directly-transmissible viruses encountered in routine clinical practice. Early intensive-care admission improves survival.
Can Sin Nombre virus spread person-to-person?
No documented person-to-person transmission has been recorded for Sin Nombre virus. This contrasts with Andes virus in southern South America, which is the only hantavirus with confirmed human-to-human spread.

Other hantavirus strains

Andes virusHPS
Long-tailed pygmy rice rat · Southern South America (Argentina,
Puumala virusHFRS
Bank vole · Northern, central, and western
Hantaan virusHFRS
Striped field mouse · East Asia (China, Korean
Seoul virusHFRS
Brown rat · Worldwide (anywhere brown rats
Reference

Read more: What is hantavirus · Symptoms · Transmission · Prevention · Historical outbreaks