Seasonal hantavirus risk levels by world region, based on rodent breeding cycles, climate patterns, and historical outbreak data.

RegionJanFebMarAprMayJunJulAugSepOctNovDec
Americas (HPS)LowLowModerateHighHighHighModerateModerateModerateLowLowLow
Europe (HFRS/PUUV)LowLowLowLowModerateModerateHighCriticalHighModerateLowLow
Asia (HFRS/HTNV)ModerateModerateHighHighModerateModerateModerateHighHighModerateModerateModerate
Global (Seoul)ModerateModerateModerateModerateModerateModerateModerateModerateModerateModerateModerateModerate
Low
Moderate
High
Critical
● = Current month

🌱 Spring (Mar–May)

  • Americas: Peak HPS season — deer mice begin nesting and breeding
  • Asia: HFRS season begins as field work increases rodent contact
  • Highest-risk time to clean winter-closed cabins, garages, barns

☀️ Summer (Jun–Aug)

  • Europe: Bank vole populations peak — highest HFRS risk for Finland, Germany, Sweden
  • Americas: HPS risk remains elevated, especially in dry Western US
  • Camping and outdoor activities increase exposure risk globally

🍂 Autumn (Sep–Nov)

  • Europe: Puumala virus infections surge as voles move indoors before winter
  • Mast years (heavy nut/seed production) drive 10x normal vole populations
  • Asia: Second seasonal peak for HFRS in Eastern Asia

❄️ Winter (Dec–Feb)

  • Americas: Lowest HPS risk — deer mouse activity reduced
  • Europe: HFRS cases decline but Seoul virus risk year-round globally
  • Indoor rodent infestations increase — seal entry points before spring