Identifying Hantavirus-Carrying Rodents — Deer Mouse, Pygmy Rice Rat, Bank Vole

Different hantaviruses circulate in different rodent species, and knowing which rodent is the local reservoir is one of the most useful pieces of practical knowledge for outdoor travelers, rural property owners, and field workers. This article gives you the field-grade identification cues for the three most relevant species globally.

Deer mouse — Peromyscus maniculatus (Sin Nombre virus, USA)

• Size: Small — body 7–10 cm, tail roughly equal to body length
• Coat: Brown to grey-brown on the back, sharply white belly (the diagnostic feature) and white feet
• Tail: Bicoloured — dark on top, white underneath, well-furred (not naked like a rat tail)
• Ears: Large relative to head, naked-skin appearance
• Eyes: Large and dark
• Distribution: Most of North America from southern Canada through Mexico, including the Four Corners region (1993 outbreak) and Yosemite (2012 cluster)
• Habitat: Cabins, sheds, woodpiles, sage scrub, forest edge. Highly adapted to human structures.

Easy confusion: Looks similar to the white-footed mouse (Peromyscus leucopus) which also carries hantaviruses (mostly New York virus); for practical purposes treat any small, white-bellied mouse with bicoloured tail in North America as a potential hantavirus reservoir.

Long-tailed pygmy rice rat — Oligoryzomys longicaudatus (Andes virus, Patagonia)

• Size: Body 7–10 cm, tail noticeably longer than body (12–15 cm) — the diagnostic feature
• Coat: Yellowish-brown or olive-brown on the back, paler grey-cream on the belly (not the bright white of the deer mouse)
• Tail: Long, slender, sparsely haired, often paler underneath
• Ears: Smaller and more rounded than deer mouse
• Snout: Pointed
• Distribution: Argentina (Río Negro, Chubut, Neuquén provinces) and Chile (Los Lagos, Aysén regions) — the Patagonian steppe and Andean foothills
• Habitat: Caña colihue bamboo thickets, lake-side vegetation, rural cabins and outbuildings — populations boom every 7–9 years when the bamboo flowers and seeds, driving outbreak clusters historically

Critical context: ANDV is the only hantavirus that spreads person-to-person, so secondary cases can occur far from this rodent's range — as the 2026 MV Hondius cluster shows.

Bank vole — Myodes glareolus (Puumala virus, Europe)

• Size: Body 8–12 cm, tail shorter than body (4–7 cm) — diagnostic vs the long-tailed pygmy rice rat
• Coat: Distinctive chestnut-red back, grey-cream sides and belly — the most recognisable feature
• Body shape: Stocky, more compact than deer mouse
• Ears: Small, partially hidden in fur
• Distribution: Most of continental Europe (especially Finland, Sweden, Germany, the Balkans, European Russia, Türkiye's Black Sea region)
• Habitat: Deciduous and mixed forests, hedgerows, gardens, rural sheds and bird-feeding stations

Bank vole-borne Puumala virus causes a much milder kidney syndrome (HFRS) — case fatality typically below 1% — quite different from the Andes virus pulmonary picture.

Important: never handle wild rodents

Identification is for situational awareness only. Never attempt to capture or handle wild rodents directly, and never disturb nests without full PPE and proper protocol — see our rodent contamination cleanup guide for the safe approach.

Related reading

• Hantavirus endemic regions worldwide
• Why the Andes strain is unique among hantaviruses
• Camping & hiking precautions