Health officials are keeping an eye on four Californians who may have been exposed to a hantavirus outbreak linked to a cruise ship from the Netherlands. This includes a Bay Area resident who was onboard the ship before showing signs of infection.
The California Department of Public Health made the announcement, stating they are collaborating with the CDC and local agencies after identifying three passengers from California on the MV Hondius, where the Andean hantavirus outbreak resulted in three fatalities.
The fourth Californian got infected after sitting near someone who had returned from the cruise during an international flight.
Authorities reassured the public that the risk of further transmission is “extremely low.”
Two individuals have already returned home and are currently being monitored by local health officials, according to the CDPH.
The last two individuals were taken by federal authorities to a secure medical facility in Nebraska. They’ll head back to California once they have completed necessary medical evaluations and safety protocols are in place.
California Public Health Officer Dr. Erica Pan acknowledged the public’s worries about this unusual outbreak, citing decades of experience in South America which indicates that the Andean hantavirus seldom spreads between people. Efforts are ongoing to monitor those potentially infected and ensure their safe return.
One of those exposed, a resident of Santa Clara County, was on the MV Hondius but disembarked before the outbreak was confirmed. Health officials from the county mentioned that this person is currently well and asymptomatic, adhering to monitoring protocols recommended by the CDC.
The other exposed Californian is from Sacramento County and was not on the ship but was also infected during an international flight.
Despite the very low risk to public health, Sacramento County officials are taking precautions seriously and are adhering to all suggested monitoring guidelines. They confirmed this individual has not exhibited any symptoms and is isolating at home.
The MV Hondius had 147 people on board—86 passengers and 61 crew members from 23 different countries when the outbreak occurred. The ship set sail from Ushuaia, Argentina, on April 1 and traversed several locations, including Antarctica and St. Helena, before the outbreak was reported.
The World Health Organization was notified on May 2 after a passenger and crew member presented severe respiratory issues.
Passengers who remained on the ship disembarked recently, with many boarding flights to various countries for quarantine.
Hantaviruses are typically transmitted through the excretions of wild rodents, and the Andean strain involved in this incident is found in Argentina and Chile, with rare instances of person-to-person transmission occurring in close, prolonged contact with infected individuals.
This strain is distinct from the Sin Nombre hantavirus native to California, which hasn’t been associated with human-to-human transmission. From 1980 to 2025, California has seen 99 reported cases of Sin Nombre infections.
Hantavirus pulmonary syndrome can be severe, starting with flu-like symptoms before leading to serious respiratory issues. The overall mortality rate is estimated at 30% to 40%, and there are no specific antiviral treatments available. Severe cases may require intensive medical interventions.
As of Monday, all four exposed Californians were reportedly asymptomatic. The CDPH indicated that their monitoring processes include daily symptom checks and activity modifications.
California’s Viral Rickettsial Disease Laboratory is among the only public health labs in the country capable of conducting validated hantavirus PCR tests for outbreak responses, enabling quicker evaluation of residents if symptoms develop.
CDPH is also collaborating with hospitals capable of treating potential hantavirus cases and issuing guidance to physicians. They reiterated that the public risk remains extremely low.
