90-Second Read: What we know about Hantavirus in western Washington

Here's what we know about the Hantavirus situation in western Washington. Valenciano, health officer and acting director for Public Health, Seattle & King County, said the county has strong contact tracing protocols that have helped contain the spread of Hantavirus in previous outbreaks. About two cases are reported per year in Washington state, mainly in eastern Washington counties, according to a 2025 state Department of Health report. Two King County residents are monitoring for Hantavirus symptoms at home, and a third person is quarantined in Nebraska.

A spokesperson for the Pierce County health department said the Centers for Disease Control and Prevention is working with international partners and state health departments to identify Americans who were exposed to Hantavirus and alert public health agencies. About one out of every three people diagnosed with Hantavirus have died. Hantavirus is already been present in Washington state, although it's a different strain than the one that spread on the MV Hondius. To stream KING 5 on your phone, you need the KING 5 app.

Health officials said the risk to the public remains low and said the residents will be monitored for weeks before the exposure window passes. Once King County public health was alerted about the possible exposure, officials contacted the two residents to confirm they were in their assigned seats on the plane where the sick passenger was removed. The protocols include daily temperature checks, assessment for symptoms and responding to daily Public Health monitoring. The virus can cause Hantavirus Pulmonary Syndrome with symptoms that typically begin four days to six weeks after inhaling the virus.

The virus that has already been reported in Washington is the Sin Nombre virus, which cannot be spread person to person. Most notably, three cases were reported in King and Skagit counties from November 2016 to June 2017. Valenciano said no additional contact tracing is necessary at this time.