Last reviewed 2026-05-14
Sin Nombre Virus vs Andes Virus
Both Sin Nombre virus and Andes virus cause hantavirus pulmonary syndrome (HPS), but they differ in geographic range, reservoir species, and — critically — whether they can spread between people. Side-by-side comparison.
Item A
Sin Nombre virus (SNV)
Hantaviridae · New World hantavirus
The dominant cause of hantavirus pulmonary syndrome in North America. First identified during the 1993 Four Corners outbreak. Reservoir is the deer mouse.
More on Sin Nombre virus (SNV) →Item B
Andes virus (ANDV)
Hantaviridae · New World hantavirus
The dominant HPS strain in southern Argentina and Chile. Notable as the only hantavirus with documented person-to-person transmission. The agent behind the 2026 MV Hondius cruise-ship outbreak.
More on Andes virus (ANDV) →Side-by-side
| Feature | Sin Nombre virus (SNV) | Andes virus (ANDV) |
|---|---|---|
| Clinical syndrome | HPS | HPS |
| Geographic range | Western United States, Canada, Mexico | Southern Argentina, southern Chile |
| Primary reservoir | Deer mouse (Peromyscus maniculatus) | Long-tailed pygmy rice rat (Oligoryzomys longicaudatus) |
| Case fatality rate | ~36% | 35–50% |
| Incubation period | 1–8 weeks | 1–8 weeks |
| Person-to-person transmission | Not documented | Documented in close-contact settings (Argentina 1996, 2018, MV Hondius 2026) |
| Year first described | 1993 | 1995 |
| Notable outbreaks | Four Corners (1993), Yosemite (2012) | Bariloche (1996), Epuyén (2018–2019), MV Hondius (2026) |
What they share
- ●Both are New World hantaviruses causing hantavirus pulmonary syndrome (HPS).
- ●Both produce a flu-like prodromal phase lasting 3–5 days followed by a rapidly progressive cardiopulmonary phase.
- ●Both have case-fatality rates above 30% and require ICU-level supportive care.
- ●Both share the same management pattern: meticulous fluid balance, mechanical ventilation, and ECMO when available.
- ●Neither has a licensed vaccine.
What sets them apart
- ●Andes virus is the only hantavirus with documented person-to-person transmission. Sin Nombre virus has never demonstrated human-to-human spread.
- ●Geographic ranges do not overlap: Sin Nombre is North American, Andes is Patagonian.
- ●Andes virus tends to cause slightly higher case-fatality rates, particularly in clusters.
- ●Reservoir species are different rodents, so prevention focuses on different ecological niches.
Bottom line
If you're investigating a possible HPS exposure in the Western United States or southwestern Canada, Sin Nombre virus is the working diagnosis. South of about Mendoza, Argentina, or in southern Chile — particularly with a cluster involving close contacts — Andes virus is the working diagnosis and human-to-human transmission must be considered.