Three Passengers Die on MV Hondius Cruise Ship from Andes Strain of Hantavirus

Three passengers aboard the expedition cruise ship MV Hondius died, triggering an international scramble to trace passengers and crew exposed to the Andes strain of hantavirus now circulating on the vessel. The outbreak prompted virologists to examine how the self-contained environment of a cruise ship enabled spread of a virus typically linked to rodent contact. Dr.

Scott Pegan, a virologist at the UC Riverside School of Medicine, compared the Andes strain situation on the MV Hondius to aspects of the early COVID-19 strain on the Diamond Princess cruise ship, which was associated with early COVID-19 transmission six years before 2026.

Pegan said the transmission of the Andes hantavirus is nosocomial, meaning hospital-acquired or close-contact spread. “It’s a hypothesis that the virus builds up a higher titer in the saliva,” Pegan said.

He noted that a cruise ship cabin is functionally the same problem as a hospital room where protective measures are not taken. Dr. Marieke Rosenbaum, a veterinary public health expert at Tufts University’s Cummings School of Veterinary Medicine, said the cruise ship represented perfect conditions for wider spread.

“The risk of human-to-human transmission of hantavirus is really low, and this cruise was just like the perfect condition for it to spread to more people than I think it might have otherwise,” Rosenbaum said. Hantavirus spreads almost entirely through aerosolized particles from rodent urine, droppings or saliva.

“Most cases, like in the United States, it’s usually because somebody is cleaning out a rat-infested area, and maybe not using sufficient PPE, mask, whatever, to do it,” Pegan said.

Rosenbaum, who has been studying urban rats in Boston for over a decade as part of the Boston Urban Rat Study, offered concrete cleaning advice. When cleaning up rodent urine or droppings one should wear gloves, wear a mask, and spray the area with water. One should not sweep or vacuum rodent droppings because it aerosolizes particles.

The most dangerous hantavirus exposures tend to happen indoors in attics, sheds, basements, or any enclosed space with limited ventilation. If a person has recently traveled to South America and starts running a fever with muscle aches, they should tell their doctor.

“If somebody comes in and they say, hey, I’ve got some muscle aches, and I recently went down to South America, they’re probably getting a blood test for hantavirus,” Pegan said.

The hantavirus blood test diagnostic is most reliable more than 72 hours after symptoms begin. Rosenbaum’s team is finishing a paper on hantavirus in Boston rats. She has a research paper coming out about finding the Seoul variant of the hantavirus in Boston rats.

Norway rats are the reservoir for Seoul virus, a hantavirus that causes hemorrhagic fever with renal syndrome. 4 million NIH grant for his work on Crimean-Congo hemorrhagic fever (CCHF) virus. His lab has developed a vaccine platform currently aimed at CCHF that could be adapted for hantaviruses.

Pegan said the vaccine platform protects in as little as three days. The only existing hantavirus vaccine, Hantavax, is only really effective against the Seoul and Hantaan virus. Dr. Stephen Kornfeld, a virology researcher, was aboard the MV Hondius as a passenger bird-watching.

Pegan said the combination of population growth, encroachment on wildlife habitat and global travel increases spillover risks. “I can safely say there’ll be another pandemic in our future,” Pegan said.