Which Mice Carry Hantavirus? The 6 Reservoir Species to Identify
Seeing a mouse in your home does not mean you are looking at a hantavirus risk. Most mouse species do not carry pathogenic hantaviruses. Each disease-causing hantavirus is associated with one specific reservoir species, and knowing which one matters in your region tells you what to actually worry about and what to ignore.
The reservoir principle
Each pathogenic hantavirus is associated with one specific rodent reservoir species. The relationship is co-evolutionary; the virus persists for the rodent's lifetime without causing illness in the host, but causes severe disease when it crosses into humans. This means a given hantavirus is found only where its reservoir species lives.
The practical implication is that the geography of hantavirus disease maps directly to the geography of specific rodent species. Areas without the reservoir species cannot sustain endemic transmission, regardless of how many other mouse species are present.
The six reservoirs you should know
1. Deer mouse (Peromyscus maniculatus)
Carries: Sin Nombre virus (HPS)
Geographic range: Most of North America from Alaska to central Mexico; absent only from the southeastern US.
Habitat: Highly adaptable. Found in forests, grasslands, deserts, agricultural areas, and human structures throughout the range.
The deer mouse is the most important hantavirus reservoir in North America. It is the species responsible for the 1993 Four Corners outbreak and the 2025 Arakawa case. Population dynamics are tied to weather cycles, with mouse booms following wet years that produce abundant food.
Identification: Small (15-20 cm including tail). White belly and white feet contrasting with grayish-brown to reddish-brown back. Large eyes and prominent ears. Bicolored tail (dark above, white below). Often confused with the white-footed mouse, which is similar in appearance and habitat but carries different (less pathogenic) hantavirus strains.
2. Cotton rat (Sigmodon hispidus)
Carries: Black Creek Canal virus and Bayou virus (both cause HPS)
Geographic range: Southern United States from Virginia through Florida and west to southern California; northern Mexico, Central America.
Habitat: Tall grasses, agricultural fields, marshy areas, brushy habitats. Less likely to enter homes than deer mice but still occurs.
Cotton rats produce fewer hantavirus cases than deer mice in the US, but the strains they carry have similar mortality. The species is larger and more cautious of humans than deer mice, which reduces but does not eliminate exposure risk.
Identification: Larger than deer mice (25-35 cm). Coarse grayish-brown fur with darker streaks. Shorter tail relative to body length than deer mice. Less likely to be seen than deer mice because of more cautious behavior.
3. Long-tailed pygmy rice rat (Oligoryzomys longicaudatus)
Carries: Andes virus (HPS, only hantavirus with documented person-to-person transmission)
Geographic range: Argentina, Chile, Uruguay, southern Brazil, parts of Bolivia.
Habitat: Forests and grasslands of southern South America, including the Patagonian region. Can enter rural buildings and seasonal cabins.
This is the reservoir for the strain involved in the 2026 MV Hondius cluster and the 2018-2019 Epuyén outbreak. Population dynamics in the Patagonian region drive periodic case clusters.
Identification: Small (about 20 cm including the proportionally very long tail, which can exceed body length). Brown to reddish-brown coloration. The long tail is the distinguishing feature. Native species; not found outside South America.
4. Striped field mouse (Apodemus agrarius)
Carries: Hantaan virus (HFRS)
Geographic range: Eastern Europe through East Asia, including China, Korea, eastern Russia.
Habitat: Grasslands, agricultural fields, brushy areas. Enters human structures in winter.
This is the original hantavirus reservoir, studied during the Korean War when Hantaan virus was first systematically investigated. Annual case counts in China and Korea (tens of thousands) reflect this reservoir's wide range and close human contact.
Identification: Small (about 18-22 cm). Yellowish-brown back with a distinctive dark stripe running from the head to the base of the tail. White belly. The dorsal stripe is the key identifying feature.
5. Bank vole (Myodes glareolus)
Carries: Puumala virus (mild HFRS)
Geographic range: Most of Europe and western Russia, including Scandinavia, the British Isles, and Eastern Europe.
Habitat: Forests, especially deciduous and mixed woodlands. Less likely to enter homes than other reservoirs but enters structures bordering forests.
Bank vole population cycles drive Puumala virus epidemic years in Finland and Sweden, where 1,000-3,000 cases occur annually. The species has 3-4 year population cycles tied to mast years (heavy seed crops) in forests.
Identification: Small (about 15 cm). Reddish-brown back, grayish belly. Rounder body and shorter tail than mice. Vole shape is distinctive: chunky body with small ears that barely protrude from the fur.
6. Brown rat (Rattus norvegicus)
Carries: Seoul virus (mild HFRS)
Geographic range: Worldwide wherever humans live. Originally native to Asia, now established globally including in pet rat populations.
Habitat: Closely associated with human structures. Urban environments, sewers, agricultural buildings, anywhere humans store food.
Seoul virus is unusual among hantaviruses for its global distribution because its reservoir is also globally distributed. Pet rats can carry Seoul virus, with sporadic cases documented in the US and UK linked to pet ownership.
Identification: Much larger than mice (30-45 cm including tail). Brown to grayish-brown fur. Tail shorter than body length. Often seen in urban environments and around food sources.
Mice that do NOT carry pathogenic hantavirus
Many common mouse species are not hantavirus reservoirs. The fact that you see a mouse does not mean you are looking at a hantavirus risk.
House mouse (Mus musculus): The most common rodent in human structures globally. House mice do NOT carry the hantaviruses that cause severe human disease. Their presence is a sanitation and damage concern but not a hantavirus concern.
White-footed mouse (Peromyscus leucopus): Common in the eastern US. Can carry some hantaviruses (like New York virus) but at much lower rates than deer mice carry Sin Nombre. The pathogenic potential of the strains it carries is also lower.
Wood mouse, harvest mouse, dormice (Europe): Various small mouse species in European forests. Not pathogenic hantavirus reservoirs.
Eastern chipmunks, ground squirrels: Not hantavirus reservoirs despite their rodent classification.
The general principle: only the six species above (and a few less-common reservoirs in specific regions) carry hantaviruses that cause severe human disease.
What to do when you see a rodent
The presence of a mouse in your home or property does not automatically require hantavirus precautions, but the response should be calibrated to your region and the species likely involved.
In endemic regions for HPS (western US, southern South America)
Treat any mouse activity as potentially involving the reservoir species. Even if you cannot identify the specific mouse, follow the CDC cleanup protocol for any droppings or nesting material. The cost of treating a non-reservoir species as if it were the reservoir is minimal; the cost of the reverse is potentially significant.
In endemic regions for HFRS (Northern Europe, East Asia)
Similar approach. Voles in forest-adjacent properties in Finland or striped field mice in agricultural areas in Korea should be treated with full cleanup protocol. Mortality for Puumala is low but morbidity is significant; mortality for Hantaan can be serious.
In non-endemic regions or with non-reservoir species
Hantavirus risk is essentially zero, but rodent control remains appropriate for other reasons. Mice carry other pathogens (including Lyme-related agents via ticks), cause property damage, contaminate food supplies, and create sanitation issues. The CDC cleanup protocol is still good practice even when hantavirus is not the specific concern.
Visual identification limits
Most homeowners are not able to definitively identify mouse species. The descriptions above provide guidance, but specific identification often requires comparing multiple features (size, color, tail proportions, habitat context) that are hard to assess from a brief sighting.
For practical purposes, the better approach is to identify by region rather than by individual mouse:
- If you are in the western US and see any small mouse with light underside in or around your home, assume it might be a deer mouse. Treat accordingly.
- If you are in Patagonia and see any small mouse, assume Andes virus reservoir is possible. Treat accordingly.
- If you are in Finland and see vole activity in forest-adjacent areas, assume Puumala reservoir is possible.
- If you are in an urban area and see a brown rat, Seoul virus is the consideration (mild but real).
This regional approach avoids the false-confidence problem of misidentifying a deer mouse as a house mouse. Both are small grayish rodents; the distinction matters for hantavirus but is hard to make reliably from a sighting.
For pest control professionals
Commercial pest control operators in endemic regions are usually familiar with the local reservoir species and appropriate handling. If you hire pest control for a rodent infestation in a hantavirus-endemic area, the cleanup protocol and disposal practices should follow CDC guidance regardless of suspected species. Reputable operators will use proper PPE and disposal practices as standard procedure.
For pet rats and pet rat breeding, Seoul virus testing is available through veterinary laboratories. The CDC has specific guidance for pet rat owners about reducing Seoul virus risk, including testing of new rats before introduction to existing rat colonies.
The simple summary
Six rodent species carry the hantaviruses that cause serious human disease, and each is concentrated in a specific geography. The deer mouse covers most of North America. The cotton rat covers the southern US. The long-tailed pygmy rice rat is the Andes virus carrier in southern South America. The striped field mouse covers East Asia and brings Hantaan. The bank vole brings Puumala in Northern European forests. The brown rat carries Seoul virus globally.
House mice and most other small rodents are not hantavirus reservoirs. The presence of any rodent in your home is a reason for control measures; only the reservoir species are reasons for specific hantavirus concern. For most people in endemic regions, knowing which species lives where you live is the most useful piece of information. The rest follows from the standard cleanup protocols and awareness.