Hantavirus infects at least 2 on cruise ship, while 5 others fall ill: Here's what we know

Editor's note: Further updates on the hantavirus cluster can be found on Live Science's live blog, which will provide the latest information on the ongoing investigation.

Two confirmed and five suspected cases of hantavirus infection have struck passengers of a cruise ship in the Atlantic Ocean.

Of the seven affected individuals, three have died and one is currently receiving intensive medical care, the World Health Organization (WHO) said in a May 4 statement. Hantavirus infections have been officially implicated in one of the deaths and in the intensive-care case. Three additional individuals are currently experiencing mild symptoms or are asymptomatic at this point.

What are hantaviruses?

Hantaviruses are a family of viruses typically carried and spread by rodents. People can catch the germs if they are exposed to the urine, droppings or saliva of infected animals, or rarely, if an infected animal bites them. One type of hantavirus, called the Andes virus, is capable of spreading from an infected person to other people, but such cases of human-to-human transmission have been rare. The specific type of hantavirus involved in the cruise ship cases has not been disclosed.

Hantaviruses can cause two types of serious infection: hantavirus pulmonary syndrome (HPS) and hemorrhagic fever with renal syndrome (HFRS). The former infection can take up to eight weeks to develop after exposure to the virus; it starts with fever, chills and fatigue and progresses to potentially deadly organ dysfunction and respiratory issues. The latter infection takes about two to four weeks to set in and causes fever, headache, gastrointestinal issues, kidney dysfunction and, sometimes, internal bleeding.

HPS is deadlier than HFRS, with a fatality rate of 38% in patients who develop respiratory symptoms of the disease. The fatality rate of HFRS varies depending on the specific hantavirus a person is infected with, with fatality rates ranging from 1% to 15%.

Treatments for hantavirus disease aim to manage a patient's symptoms; there is no cure for the infections.

"While there are no specific treatment nor vaccines for hantavirus infections, early supportive care and immediate referral to a facility with a complete ICU can improve survival," the WHO states.

What happened on the cruise?

So far, only one of the illnesses connected to the cruise has been confirmed to be a hantavirus infection, according to the cruise's operator, Oceanwide Expeditions. The company, which offers expedition-style voyages to the polar regions and sub-Antarctic, detailed the situation in statements released May 3 and May 4.

The affected vessel is the MV Hondius, which departed from Ushuaia in Argentina on April 1, was carrying a total of 147 individuals, including 88 passengers and 59 crew members. After departure, it traveled across the southern Atlantic, stopping in mainland Antarctica, South Georgia, Nightingale Island, Tristan da Cunha, St. Helena and Ascension Island. The ship is currently off the coast of Cape Verde.

"The extent of passenger contact with local wildlife during the voyage, or prior to boarding in Ushuaia remains undetermined," the WHO noted in its May 4 update. The agency has been told there are no rodents on the ship itself.

On April 6, a passenger developed fever, headache and mild diarrhea, and five days later, he died on board of respiratory distress. His cause of death could not immediately be determined and no laboratory tests were conducted.

On April 24, that deceased passenger and his surviving wife, both Dutch nationals, were dropped off on St. Helena to await repatriation to the Netherlands. She had gastrointestinal symptoms at the time. The following day, she boarded a flight to Johannesburg, South Africa, and her condition worsened, and she died upon arrival at an emergency department on April 26. As of May 4, her case was confirmed to be caused by a hantavirus via a laboratory exam, the WHO reported..

These two passengers had traveled in South America, including in Argentina, prior to boarding MV Hondius.

Meanwhile, on April 24, another passenger got sick with symptoms of fever, shortness of breath and signs of pneumonia. He was evacuated from Ascension Island to South Africa for treatment after his condition worsened. The passenger, a British national, remains in intensive care in Johannesburg and is in "critical but stable condition." Laboratory tests have confirmed that a hantavirus infected this patient.

Back on MV Hondius, another passenger died on May 2 after developing a fever on April 28. Her condition had progressed to pneumonia before she died.

Then, three additional people on board developed fever or gastrointestinal symptoms.

Maria Van Kerkhove, the WHO's interim director of epidemic and pandemic preparedness and prevention, gave an update on the situation on May 4. The patient in intensive care is improving, while two sick individuals onboard are being prepared for evacuation to the Netherlands for treatment, she said. The third sick individual is now asymptomatic.

"The situation is being closely monitored," Van Kerkhove said. DNA analysis of the viruses sampled from the confirmed hantavirus infections is taking place now, along with medical examinations of the people with suspected cases, contact tracing and investigations to determine the original source of infection, she said. Once the two sick passengers are evacuated, the plan is for MV Hondius to go to the Canary Islands so a full investigation of the outbreak and disinfection of the ship can take place.

Based on the information available about the outbreak and what is known about hantaviruses, the WHO judges the current risk to the general public as low.

Is human-to-human transmission to blame?

To date, the Andes virus, found in Chile and Argentina, is the only hantavirus with strong evidence of human-to-human transmission. "For other hantaviruses, transmission is believed to occur almost exclusively from rodents to humans," Luis Escobar, an assistant professor in Virginia Tech's Department of Fish and Wildlife Conservation, told Live Science in an email.

Escobar's lab researches the biogeography, ecology and evolution of infectious diseases, including hantaviruses. He noted that scientists don't yet understand which biological features of the Andes virus make it capable of spreading between people.

It's been difficult to pin down exactly how infectious the virus is to people, in part because public health authorities in Chile and Argentina have been quick to act in instances when human-to-human spread was suspected. Measures like contact tracing, isolation and monitoring have limited the virus's spread, meaning there's little data regarding its transmission between people.

"While it cannot be completely excluded that other hantaviruses [in addition to the Andes virus] might have some capacity for person‑to‑person spread, there is currently no convincing evidence that this happens," he told Live Science. "But research has been limited."

Current evidence does suggest that different flavors of hantavirus have distinct traits. For example, hantaviruses in North America and South America can infect a greater variety of rodent species than hantaviruses in Europe and Asia can. Although this flexibility doesn't necessarily make the viruses in the Americas more likely to infect people, it does suggest "a greater tendency to cross species boundaries," Escobar said. These differences among hantaviruses are an active area of study.

The WHO and other health authorities are still investigating the source of the cruise ship infections and whether human-to-human spread might be at play. If an Andes virus from South America is to blame, human-to-human spread wouldn't be a total surprise. However, if a different hantavirus is the culprit, that could be significant.

"I would be surprised if authorities were to find some evidence of human‑to‑human transmission caused by a hantavirus other than Andes virus," Escobar said. "Such a finding would fundamentally change our current understanding of hantavirus biology and would signal a much greater epidemic and pandemic risk than has ever been documented for this group of viruses."

"We are working under the assumption that it's the Andres virus," Van Kerkhove said in the May 4 update. At this juncture, the WHO's working hypothesis is that at least one of the two initial cases were infected before boarding the ship and that some degree of human-to-human transmission took place onboard between close contacts. That said, it's also possible that others who fell ill were exposed to the virus during one of the additional stops that the ship made on its journey, she said.

Editor's note: This article was last updated at 3:30 p.m. on May 5, 2026. The story was first published at 1 p.m. on May 4, 2026.