For hantaviruses, human infections are accidental and almost always dead ends. Transmission to people generally happens when virus-laden rodent excreta gets stirred up in dust and inhaled—for example, a person sweeping out a shed or garage with a rodent infestation without a mask.

Such a scenario made headlines in the US last year when pianist Betsy Arakawa, who was married to actor Gene Hackman, was revealed to have died of hantavirus. A subsequent investigation found an extensive rodent infestation at the couple’s residence.

The one exception to this transmission route is from the Andes virus; ANDV is the only hantavirus that has been documented in rare instances to spread from person to person.

Based on that documented incidence, it is clear that person-to-person transmission requires close, prolonged contact. To date, though, it remains unclear whether breathing significant amounts of aerosolized virus from an infected person or exposure to an infected person’s respiratory droplets is behind the rare transmission. //

Whether from rodent exposure or the ultra-rare person-to-person transmission, the incubation period for hantaviruses—the amount of time between exposure and when symptoms develop—ranges from about 7 to 42 days.

The currently recommended quarantine and/or active monitoring period for potentially exposed cases is 42 days.