Hantavirus Risk Areas: US State Data & Global Map
Hantavirus Pulmonary Syndrome (HPS) is concentrated in the western United States, with the highest cumulative case counts in New Mexico, Colorado, and Arizona since surveillance began in 1993. This guide covers US state-by-state data and global endemic regions to help you assess risk before travel or outdoor activities.
🇺🇸 Hantavirus Risk by US State
Data represents cumulative confirmed HPS cases from 1993–2023 per CDC surveillance. Eastern US states have reported fewer than 5 cases total; eastern HPS risk is considered very low. The concentration in western states reflects the distribution of the deer mouse (Peromyscus maniculatus), the primary Sin Nombre virus reservoir.
| State | Total Cases (1993–2023) | Risk Level | Primary Strain | Notes |
|---|---|---|---|---|
| New Mexico | 121 | very high | Sin Nombre | Highest US case count; Navajo and Apache counties most affected |
| Colorado | 108 | very high | Sin Nombre | Wide distribution across rural counties; camping and agricultural exposure |
| Arizona | 87 | very high | Sin Nombre | 7 cases in 2025; significant ongoing transmission |
| California | 72 | high | Sin Nombre | 3 deaths Mammoth Lakes 2025; Sierra Nevada foothills highest risk |
| Washington | 55 | high | Sin Nombre | Eastern WA Cascade foothills; cabin exposure common |
| Montana | 42 | high | Sin Nombre | Rural agricultural areas; hay storage and barn work risk |
| Utah | 38 | high | Sin Nombre | Four Corners area and Colorado Plateau |
| Texas | 36 | moderate | Sin Nombre / Black Creek Canal | West Texas rural areas; Black Creek Canal in SE |
| Oregon | 27 | moderate | Sin Nombre | Eastern Oregon semi-arid regions |
| Wyoming | 24 | moderate | Sin Nombre | Rural areas; Greater Yellowstone Ecosystem |
| Idaho | 19 | moderate | Sin Nombre | Southern Idaho agricultural areas |
| South Dakota | 18 | moderate | Sin Nombre | Western SD badlands and ranching areas |
| Nebraska | 15 | low moderate | Sin Nombre | Western Nebraska Sandhills and ranching |
| Nevada | 14 | low moderate | Sin Nombre | Rural areas; low population density limits surveillance |
| Kansas | 11 | low moderate | Sin Nombre | Western plains farmland |
| North Dakota | 8 | low moderate | Sin Nombre | Prairie farmland; grain storage sites |
| Minnesota | 7 | low moderate | Sin Nombre / Seoul | Seoul virus in pet rat owners; SNV in western counties |
| Florida | 4 | low | Black Creek Canal | Distinct strain; cotton rat reservoir in southern FL |
| All other states | 24 | low | Seoul virus (some) | Mostly Seoul virus in pet/feeder rat breeders; HPS risk negligible |
Seoul virus (mild HFRS, not HPS) has been reported in pet rat owners and rat-breeding facilities across multiple US states including Michigan, Illinois, Wisconsin, and Georgia. This is clinically distinct from HPS and is generally a milder illness. If you breed pet rats and develop fever and kidney symptoms, mention this to your doctor.
Data: CDC Hantavirus Surveillance, 1993–2023. Risk levels are approximate and reflect historical exposure patterns; actual risk varies by local habitat, season, and individual behavior. Eastern US states with <5 total cases classified as 'low'.
🌍 Global Hantavirus Distribution
Hantavirus is a global disease family. While HPS captures media attention in the Americas, the Old World HFRS strains cause a far greater absolute number of hospitalizations worldwide — primarily in East Asia and Europe.
🇺🇸 United States (Western)
Strains: Sin Nombre (HPS), Black Creek Canal, Bayou
890+ HPS cases 1993–2023. Peak risk in spring–summer. Western states (NM, CO, AZ, CA) account for 75%+ of cases.
🇦🇷🇨🇱 Patagonia (Argentina / Chile)
Strains: Andes virus (ANDV) — person-to-person capable
Primary Andes virus endemic zone. Rural forested areas of Rio Negro, Neuquén, Chubut provinces. Risk for international travelers hiking or staying in rural cabins.
🇧🇷 Brazil
Strains: Multiple: Araraquara, Juquitiba, Castelo dos Sonhos
Highest Americas case count outside US. Cerrado and Atlantic Forest biomes. Agricultural exposure dominant.
🇨🇳🇰🇷 East Asia (China, Korea)
Strains: Hantaan virus (HTNV), Seoul virus (SEOV)
50,000–100,000 HFRS hospitalizations annually in China. Vaccines available for Hantaan and Seoul strains. Rural agricultural communities most affected.
🇫🇮🇸🇪 Northern Europe (Finland, Sweden, Belgium, France)
Strains: Puumala virus — causes Nephropathia Epidemica (NE)
Follows 3–4 year bank vole population cycles. Finland typically 1,000–3,000 NE cases/year in peak vole years. Mild disease; very low mortality (<0.5%).
🇷🇸🇭🇷 Balkans (Serbia, Croatia, Slovenia)
Strains: Dobrava-Belgrade virus (DOBV)
Sporadic clusters in rural Balkan regions. Higher case fatality than Puumala (5–12%). Yellow-necked mouse reservoir.
🌏 Worldwide (Seoul virus)
Strains: Seoul virus — carried by brown/Norway rat (Rattus norvegicus)
The only hantavirus with global distribution via rat transport. Causes mild HFRS. Risk primarily in rat breeders, pet rat owners, and agricultural workers. Not an HPS risk.
📊 Americas Hantavirus Data 2025
The Pan American Health Organization (PAHO) reported 229 confirmed HPS/HCPS cases across 8 countries in the Americas in 2025, with 59 deaths — a case fatality rate of 25.8%. Brazil and Argentina account for the majority of cases.
| Country | Cases (2025) | Deaths (2025) | CFR | Primary Strain |
|---|---|---|---|---|
| Brazil | 98 | 26 | 27% | Araraquara, Juquitiba |
| Argentina | 54 | 14 | 26% | Andes (ANDV) |
| Chile | 31 | 8 | 26% | Andes (ANDV) |
| Bolivia | 18 | 5 | 28% | Rio Mamore, Laguna Negra |
| Panama | 11 | 3 | 27% | Choclo virus |
| Paraguay | 9 | 2 | 22% | Laguna Negra |
| Uruguay | 5 | 1 | 20% | Andes (ANDV) |
| Venezuela | 3 | 0 | 0% | Unknown/multiple |
| TOTAL | 229 | 59 | 25.8% | Source: PAHO 2025 |
📅 Seasonal Hantavirus Risk Patterns
In the United States, hantavirus cases cluster in spring and summer (May–September), peaking in June and July. This pattern reflects:
- Increased outdoor activity: Opening cabins and vacation properties after winter closure creates the classic high-risk cleaning scenario. Agricultural season brings workers into contact with grain storage and hay.
- Rodent population cycles: Deer mouse populations expand in warm months with abundant food. El Niño years (with wetter winters producing abundant vegetation and seeds) are consistently followed by elevated HPS case counts the following spring and summer.
- Camping and hiking season: National park visitation peaks in summer, bringing more people into deer mouse habitat. The 2012 Yosemite outbreak occurred at the peak of summer season.
In South America, Andes virus transmission shows a different pattern, with cases occurring throughout the year in endemic Patagonian regions of Argentina and Chile. Agricultural activities (grain harvest in particular) drive transmission peaks there.
In Europe, Puumala virus (Nephropathia Epidemica) follows a 3–4 year cycle tied to bank vole population dynamics — "vole years" with unusually high vole density produce epidemics of NE cases in Finland, Sweden, Belgium, and France.
📌 Recent Notable US Hantavirus Events (2024–2026)
- 2025 — Mammoth Lakes, California: 3 deaths from HPS linked to rodent exposure in rental properties and ski lodge facilities. California Department of Public Health issued a regional advisory.
- 2025 — Arizona: 7 confirmed HPS cases, 4 deaths — above the recent annual average. Navajo and Apache counties most affected.
- 2025 — New Mexico: 5 cases, 2 deaths. Continued surveillance in the state with the highest historical cumulative case count.
- 2026 — Global (MV Hondius): First multi-country hantavirus cluster involving international travel and person-to-person Andes virus transmission. Full outbreak report →
Hantavirus Risk Areas FAQ
Which US state has the most hantavirus cases?
New Mexico has the highest cumulative total of HPS cases since surveillance began in 1993, with 121 confirmed cases through 2023. Colorado (108 cases) and Arizona (87 cases) follow closely. Together, these three states account for approximately 36% of all US HPS cases. The concentration reflects the highest density deer mouse populations in the country combined with rural populations and agricultural activity.
Is there hantavirus in the eastern United States?
HPS is extremely rare in the eastern US. Sin Nombre virus — the main cause of HPS — is primarily a western deer mouse-associated pathogen. Two other strains are present in the east: Black Creek Canal virus in Florida (cotton rat reservoir) and Bayou virus in the south-central states (rice rat reservoir), but these have caused very few documented HPS cases. Seoul virus has been found in domestic rat breeders in multiple eastern states but causes mild HFRS rather than HPS.
Can you get hantavirus in Europe?
Yes, but the disease is different. Europe has Puumala virus (causing Nephropathia Epidemica — a mild kidney disease with very low mortality) and Dobrava-Belgrade virus in the Balkans (more severe HFRS). Neither strain causes HPS as seen in the Americas. The risk varies by country: Finland, Sweden, Belgium, and France see the most Puumala cases. Serbia and Croatia see Dobrava cases.
Is it safe to travel to Patagonia?
Yes — millions travel to Patagonia safely each year. The risk of Andes virus from rodent exposure is real but low for typical tourists who stay in established hotels and hostels. The risk is higher for hikers camping in remote areas, hunters, agricultural workers, and people staying in rural cabins or refugios where rodent activity is common. Take standard precautions: don't sleep on the ground, store food in sealed containers, avoid cabins with visible rodent activity, and monitor for symptoms for 6 weeks after return.
What months is hantavirus risk highest in the US?
HPS cases in the US cluster most heavily in May through September, with the peak in June and July. This reflects increased outdoor activity (opening cabins, camping, agricultural work) combined with peak deer mouse population densities in spring/summer. However, hantavirus can be contracted year-round wherever infected rodents are present indoors. Winter cabin opening in late winter/early spring is also a documented high-risk scenario.