How do you catch hantavirus?

Humans almost always catch hantavirus from rodents, not from each other. The virus is shed in rodent urine, droppings and saliva. When dried excreta are disturbed — by sweeping, vacuuming, moving stored boxes, or working in dusty barns and cabins — virus particles aerosolise and are inhaled.

Documented transmission routes

• Inhalation of aerosolised rodent excreta in enclosed spaces — by far the most common route.
• Direct contact with rodent excreta or contaminated surfaces, especially if hands then touch the eyes, nose or mouth.
• Bite from an infected rodent (rare).
• Contaminated food, where rodents have urinated on stored grain or pantry contents (rare, mostly HFRS).
• Person-to-person, documented only for Andes virus (ANDV) in southern South America.

Highest-risk activities

Cleaning out a long-closed cabin, shed, garage or barn; handling stored firewood that has been nested in; harvesting or threshing grain stored outdoors; rodent-trapping; and field work in rural environments where the relevant reservoir species is active. The CDC's "open up, air out, wet down" protocol — ventilate for 30 minutes, then disinfect with bleach before sweeping — substantially reduces aerosol risk.

Hantavirus is not spread by mosquitoes or ticks, and (other than ANDV) is not spread by casual contact with infected people.