90-Second Read: 4th King County resident monitored for possible Hantavirus exposure, Public Health says

A fourth local resident is being monitored after they were aboard a flight with an ill cruise ship passenger, according to Public Health. Three additional King County residents are also being monitored for possible Andes type of Hantavirus infections after exposure. In Chelan County, a resident has tested positive for the Sin Nombre virus strain of Hantavirus, according to the Chelan-Douglas Health District.

The Washington State Department of Health and the Centers for Disease Control and Prevention (CDC) notified the local health agency about the monitoring on Thursday, May 14. The King County resident remains asymptomatic and health officials are monitoring for any developing symptoms. Another King County resident who was on the MV Hondius cruise ship is also being monitored at the national quarantine center in Nebraska.

None of the King County residents under monitoring have any symptoms and there are no Andes type infections in the county, according to Public Health. About two cases are reported per year in Washington state, mainly in eastern Washington counties, according to a 2025 state Department of Health report. Public Health said the fourth person is considered "low risk" of infection because they were not seated near the ill passenger.