Reservoir hosts and ecology
Every hantavirus species has co-evolved with one or a few closely related rodent species over millions of years. The geography of human disease therefore mirrors the geography of the host rodent, and outbreaks are tightly linked to rodent population dynamics driven by climate and food availability.
Long-tailed pygmy rice rat (Oligoryzomys longicaudatus)
The reservoir for Andes orthohantavirus. A small (20-30 g) nocturnal rodent native to the southern Andes and Patagonia, ranging from central Chile through Tierra del Fuego and into adjacent Argentina. It thrives in disturbed habitats — woodlands, fence lines, rural outbuildings — and population booms ('ratadas') driven by Chusquea bamboo mast events have repeatedly preceded ANDV outbreaks. Seroprevalence in wild colonies can exceed 30%.
Deer mouse (Peromyscus maniculatus)
The reservoir for Sin Nombre virus across western North America. Highly adaptable, the deer mouse is found in forests, grasslands and human structures from northern Mexico to the boreal forest. Pinyon-pine mast years and El Niño-driven precipitation correlate with population irruptions and subsequent HPS clusters, as observed before the 1993 Four Corners outbreak.
Bank vole (Myodes glareolus)
The reservoir for Puumala virus, the cause of nephropathia epidemica — the milder form of HFRS — across Europe. Bank vole populations boom every 3-4 years in Scandinavia and central Europe in response to oak and beech mast, driving cyclical epidemics in Finland, Sweden, Belgium and Germany.
Striped field mouse (Apodemus agrarius)
The reservoir for Hantaan virus, the cause of severe HFRS in East Asia. Ranges across mainland China, Korea and parts of Russia. Outbreaks correlate with agricultural cycles — particularly rice harvest periods when mice congregate in stored grain.
Norway rat (Rattus norvegicus)
Reservoir for Seoul virus, which has a worldwide distribution because Norway rats are commensal with humans. Seoul virus produces HFRS with renal predominance and is occasionally identified in urban outbreaks far from Asia, including in pet rats. Importantly, Seoul virus does not cause HPS.
Climate and spillover
Multiple lines of evidence link climate variability — ENSO cycles, regional precipitation anomalies, mast events — to rodent population booms and subsequent human cases. Habitat fragmentation, agricultural intensification and rural housing density modulate the human side of the spillover equation. Long-term climate change is expected to shift reservoir ranges and may expand the geography of hantavirus risk, though the direction varies by species and region.
- •Oligoryzomys longicaudatus — ANDV — Patagonia & southern Andes
- •Peromyscus maniculatus — Sin Nombre — western North America
- •Myodes glareolus — Puumala — Europe
- •Apodemus agrarius — Hantaan — East Asia
- •Rattus norvegicus — Seoul — worldwide commensal