Cases of Hantavirus by State: What You Need to Know (2026 Updates)
Hantavirus pulmonary syndrome (HPS) is a rare but often deadly respiratory illness transmitted through contact with infected rodents or their droppings.
While uncommon, the disease continues to surface in scattered cases each year — most often in the western United States, particularly in the Four Corners region of New Mexico, Colorado, Arizona, and Utah.
Below, you’ll find a refreshed 2026 update with the most recent CDC reporting we have available, including updated cases-by-state totals and noteworthy events from 2025 and early 2026.
Hantavirus Cases by State
According to the CDC data, 864 cases of the hantavirus disease were reported in the United States between 1993 and 2022. A vast majority — 94 percent — of those cases have come west of the Mississippi River.
And while they haven't updated their resource page since, we have used CDC's National Notifiable Diseases Surveillance System (NNDSS) weekly tables to reflect 2023-2025 totals.
Hantavirus (HPS) Cases by State — 2020–2025
| State | 2025 | 2024 | 2023 | 2022 | 2021 | 2020 | Total (2020–2025) |
|---|---|---|---|---|---|---|---|
| Arizona | 6 | 10 | 5 | 1 | 0 | 4 | 26 |
| California | 6 | 2 | 1 | 0 | 1 | 2 | 12 |
| Colorado | 4 | 5 | 0 | 0 | 3 | 1 | 13 |
| Idaho | 2 | 0 | 1 | 0 | 1 | 0 | 4 |
| Illinois | 1 | 0 | 0 | 0 | 0 | 0 | 1 |
| Kentucky | 1 | 0 | 0 | 0 | 0 | 0 | 1 |
| Louisiana | 0 | 0 | 1 | 0 | 0 | 0 | 1 |
| Maine | 1 | 0 | 0 | 0 | 0 | 0 | 1 |
| Montana | 0 | 0 | 0 | 0 | 3 | 0 | 3 |
| Nevada | 5 | 1 | 3 | 1 | 1 | 1 | 12 |
| New Mexico | 7 | 6 | 7 | 3 | 1 | 1 | 25 |
| North Dakota | 0 | 0 | 0 | 1 | 2 | 0 | 3 |
| Oklahoma | 0 | 0 | 0 | 1 | 0 | 0 | 1 |
| Oregon | 3 | 0 | 0 | 1 | 0 | 2 | 6 |
| South Dakota | 0 | 0 | 0 | 1 | 0 | 1 | 2 |
| Texas | 0 | 0 | 0 | 0 | 1 | 0 | 1 |
| Utah | 0 | 0 | 1 | 1 | 0 | 1 | 3 |
| Washington | 1 | 2 | 0 | 0 | 1 | 0 | 4 |
| West Virginia | 1 | 0 | 0 | 0 | 0 | 0 | 1 |
| Wyoming | 0 | 0 | 0 | 1 | 0 | 1 | 2 |
| All Other States | 0 | 0 | 0 | 2 | 2 | 3 | 7 |
| Total Cases | 38 | 26 | 19 | 13 | 16 | 17 | 129 |
Over the course of the last five years of reported data (2020-2025), Arizona claimed the most confirmed cases of hantavirus (26), with New Mexico (25) and Colorado (13) following.
Below, you can see a map from the CDC showcasing all the reported cases between 1993 and 2022, with New Mexico (122), Colorado (119), and Arizona (86) leading the way.
Major Hantavirus Outbreaks and Events in 2025 & 2026
1. San Diego County, California — First Positive Hantavirus Mouse Reported in 2026
In January 2026, San Diego County reported that a Western harvest mouse found near the Los Peñasquitos Ranch House tested positive for hantavirus — the country's first positive rodent detection reported in 2026. While this isn’t the same thing as a confirmed human case, it’s a timely reminder that hantavirus risk starts with rodent activity.
2. Mono County, California – Three Fatalities Raise Alarm
Mono County reported three fatal cases of Hantavirus Pulmonary Syndrome (HPS), including the death of a 26-year-old hotel employee. Health officials noted that none of the victims had engaged in typical high-risk activities, suggesting possible exposure during routine daily activities. Rodent droppings were found at the victims’ workplaces, prompting concerns about increased indoor rodent activity in Mammoth Lakes.
3. New Mexico – First HPS Case of the Year
A 65-year-old woman from Santa Fe County was confirmed as New Mexico’s first HPS case in 2025. This underscores the ongoing presence of hantavirus in the region, particularly in the northwestern part of the state.
4. Betsy Arakawa’s Death Highlights Risks
Betsy Arakawa, wife of actor Gene Hackman, died from HPS in their Santa Fe home. Her death brought national attention to the dangers of hantavirus, especially in areas where the virus is endemic.
5. Louisiana – Bayou Virus Cases
Two unrelated cases of HPS caused by the Bayou virus were reported in Louisiana. One patient died, and the other required intensive care. Genetic sequencing indicated that these were separate spillover events from rodents, highlighting the virus’s presence in the southeastern U.S.
6. Expanded Rodent Carriers in New Mexico
University of New Mexico researchers discovered that over 30 small mammal species in the state carry live hantavirus, including ground squirrels and chipmunks. This finding suggests a broader range of potential carriers beyond the commonly known deer mouse.
How Do You Contract Hantavirus?
Hantavirus is a result of direct exposure to rodents, with the deer mouse posing the most-common threat. It cannot be transmitted from person to person, but the virus can remain infectious on surfaces for several days. There have been several instances of localized outbreaks, including a 2012 case in Yosemite National Park that infected 10 people, killing three.
While cats and dogs cannot directly transmit the virus directly to humans either, it is possible for them to increase risk by bringing rodents into closer proximity.
Spotting the infection in rodents is difficult to impossible, so it is important to avoid all contact. Transmission can occur through direct contact, by breathing in contaminated air particles, by handling droppings or nesting materials, or by eating contaminated food.
via the CDC
What Percentage of Deer Mice Have Hantavirus?
An estimated 15 percent of deer mice carry the hantavirus.
Symptoms of Hantavirus
Signs of an infection may not present themselves for upwards of a month after contact with the infected rodent. Initial symptoms resemble the flu: fatigue, headaches, muscle pain, nausea, and fever.
After about a week, some may begin to recover. Others, though, will develop a severe shortness of breath as fluid begins to fill their lungs, requiring immediate medical attention. There is no known cure for hantavirus, so early treatment is critical.
What is the Hantavirus Mortality Rate?
Hantavirus can be extremely fatal, with a 35 percent mortality rate since 1993.
Hantavirus Prevention: 3 Steps to Staying Safe
1. Never handle rodent waste or debris without protection
If you find your home, garage, or vehicle facing a rodent problem, gear up with rubber gloves and an N95 mask. While direct contact with rodent urine and droppings is a major risk factor, so is the inhalation of waste particles. Spray all debris with disinfectant and let soak for several minutes before wiping up to avoid brushing the virus into the air.
2. Remove all mice from the area and clean everything
Use mice traps and bait stations to remove the mice from your home or garage in the case of serious infestations. Avoid glue traps and live traps as they can scare the rodent into urinating, increasing the chances of contamination. Simple snap traps with peanut butter bait can work well when placed strategically in and around areas of rodent activity.
Once you’ve removed the rodents from the area, it is important to clean thoroughly. Mice can leave pheromones that serve as road signs back to your home. A Clorox bleach solution (1.5 cups bleach in a gallon of water) is an effective tool.
3. Secure your home and garage against rodents
To prevent further contamination, check your home or garage for any cracks or holes that could serve as an entryway for rodents and fill with steel wool or caulk. It is also important to remove any rodent attractors from the area, including garbage, stored food, and nesting material.
For additional protection, the Box-Kat mouse barrier provides a foolproof fence that can be used to keep mice from reaching your car, home, or storage area. Its patented flex-panel design allows it to adapt seamlessly to uneven surfaces for indoor or outdoor use.
