Here’s what you’ll learn when you read this story:

• Diseases spreading aboard cruise ships isn’t anything new, but a rare outbreak of hantavirus is currently spreading on a cruise ship currently bound for the Canary Islands.
• The World Health Organization (WHO) has confirmed deaths of individuals exposed to an Andes strain of the hantavirus, which is typically transferred from rodents to humans, though experts suspect human-to-human transmission may be playing a role.
• Once the ship arrives at the Canary Islands, the 150 or so remaining passengers and crew will be treated and then released to their home countries.

Today’s modern cruise ships are like floating cities, replete with a variety of restaurants, shops, entertainment, and even casinos. But like any place where humans congregate, whether big boats or massive metropolises, disease inevitably follows. The most famous example in recent memory is the Diamond Princess, which experienced an outbreak of coronavirus in 2020 during the COVID-19 pandemic, but a report analyzing studies from cruise ships from 1990 to 2013 found 127 cases of norovirus outbreaks from contaminated food or human-to-human spread. In other words, if you go on a cruise, you sometimes come back with more than just souvenirs.

Unfortunately, cruise ships grabbed headlines again this week as passengers aboard the ship MV Hondius currently are not allowed to disembark in Praia, Cape Verde, due to a deadly outbreak of hantavirus, a disease typically known to transmit between rodents and humans. However, the World Health Organization (WHO) says that this curious case represents an extremely rare example of a human-to-human transmission of a species of hantavirus that originated in the Andes mountains.

“Although uncommon, limited human to human transmission has been reported in previous outbreaks of Andes virus (a specific species of hantavirus),” according to a statement the WHO released on Monday. “WHO currently assesses the risk to the global population from this event as low and will continue to monitor the epidemiological situation and update the risk assessment.”

While rare, hantavirus can be deadly serious if contracted. According to the Centers for Disease Control and Prevention (CDC), the virus often spreads through the urine, droppings, or saliva of rodents, such as the deer mouse in North America or the long-tailed pygmy rice rat (the main reservoir for the Andes hantavirus in South America). At least 20 species of hantavirus are known throughout the world, but it’s only the Andes version that has a history of a human-to-human transmission. And the MV Hondius’ port of origin? Ushuaia, Argentina.

Once contracted, the virus can wreak havoc on the body by invading tiny blood vessels known as capillaries, which then leak fluid into the lungs, causing severe respiratory distress. According to the CDC, around one-third of patients who experience respiratory symptoms will likely die from the virus.

On April 1, 2026, the MV Hondius left its port of origin with a long itinerary along the South Atlantic, even including a stop at the Antarctic mainland. NPR reports that the first death aboard the MV Hondius came one week into the trip, a man who reportedly traveled and stayed in Argentina before boarding the cruise. A report by Argentina’s Ministry of Health confirmed a recent increase in deaths related to hantavirus that starting in mid-2025, likely because of increased interactions between rodents and humans related to climate change and habitat encroachment. Notably, the closest area of possible infection was nearly 1,000 miles away from the ship’s port of call in Ushuaia. But it typically takes weeks or even more than a month for symptoms to present, so the first passenger to die from the disease may have been the original vector if he traveled through Argentina and then brought the virus onboard. To date, there have been three confirmed deaths, and 150 or so passengers remain on the MV Hondius with three more being evacuated on May 6. The ship is now headed toward the Canary Islands, where crew and passengers will be treated and then transferred to their home countries.

“The risk to the general public is low,” Maria Van Kerkhove, the WHO’s head of epidemic and pandemic preparedness and prevention, said at a news conference in Geneva. “This is not a virus that spreads like flu or like Covid. It’s quite different.”