Fourth King County resident monitored in cruise ship hantavirus outbreak

A fourth King County resident was added to public-health monitoring after officials linked possible Andes-type hantavirus exposure to the MV Hondius cruise ship and a Johannesburg-to-Amsterdam flight, a rare and logistically difficult trail to follow across a mobile passenger population.

Public Health – Seattle & King County said on May 12 that three residents were already being monitored. Two had been seated near an ill passenger on the flight from Johannesburg to Amsterdam, and a third had been a passenger aboard the MV Hondius and was being monitored at the National Quarantine Center at the University of Nebraska Medical Center in Omaha. On May 15, county officials said a fourth resident was also being monitored. That person had been on the same flight but was not seated near the ill passenger.

County officials said there were no cases of Andes-type hantavirus in King County and that the public risk remained low. The case tracking has stretched far beyond Washington, reaching passengers, federal health authorities and quarantine facilities in Nebraska as officials worked to trace who may have been exposed and where.

The World Health Organization said the outbreak was first reported on May 2 and involved a Dutch-flagged cruise ship carrying 147 passengers and crew from 23 countries. As of May 4, WHO said there were seven cases, including three deaths, with illness onset ranging from April 6 to April 28. The Centers for Disease Control and Prevention later said WHO had reported eight cases by May 8, still including three deaths.

CDC said the U.S. government was actively monitoring and responding to the outbreak, and that the risk to the American public remained extremely low. American passengers were being repatriated to Offutt Air Force Base in Omaha and then to the National Quarantine Center for further medical monitoring.

The public-health concern is unusual because Andes virus is the only hantavirus documented to spread person-to-person, and even then the CDC says that spread is rare and has typically required close, prolonged contact with a symptomatic person. Washington health officials say deer mice are the main hantavirus reservoir in the state, and that hantavirus pulmonary syndrome can begin with fever and flu-like symptoms before progressing to respiratory failure and shock.

CDC says U.S. hantavirus surveillance began after the 1993 Four Corners outbreak, and hantavirus pulmonary syndrome became nationally notifiable in 1995. Dr. Sandra J. Valenciano, the county health officer, said Public Health – Seattle & King County has strong contact tracing and monitoring in place and that this situation is very different from COVID-19 because hantavirus is already well understood.