Hantavirus That Can Spread Between Humans May Be Involved in Cruise Ship Outbreak

Infectious disease experts suspect that Andes virus, a type of hantavirus that causes cardiopulmonary syndrome, is responsible for an outbreak aboard a small cruise ship that has killed three people and potentially infected at least four others.

Andes virus, which is found in Argentina and other South American countries, has been shown to transmit from person to person.

“I think it’s likely that this is going to turn out to be Andes virus and there may have been a cluster of human-to-human transmission,” James Lawler, MD, MPH, of the University of Nebraska Medical Center’s Global Center for Health Security in Omaha, told MedPage Today.

Aneesh Mehta, MD, of Emory University in Atlanta and the National Emerging Special Pathogens Training and Education Center (NETEC), agreed that Andes virus is likely, given the number of severe cases and the cruise origination in Argentina. That raises alarms about broader spread of the virus, he said.

“The case fatality rate is quite high, and quite impactful on healthcare systems trying to care for these individuals because they’re very sick and progress to death quickly,” Mehta told MedPage Today.

An outbreak of Andes virus in Argentina that ran from November 2018 through February 2019 resulted in 34 confirmed infections and 11 deaths, according to a report in the New England Journal of Medicine. There was a single introduction of Andes virus from a rodent reservoir into humans, and then transmission was driven by three symptomatic people who attended crowded social events.

That virus was similar to the strain involved in the first person-to-person transmission of hantavirus cardiopulmonary syndrome caused by Andes virus, which occurred in Argentina in 1996, researchers reported.

Several other instances of human-to-human transmission, mostly in Argentina but also in Chile, have been reported in the literature.

Lawler noted that it’s possible that cruise ship guests “all could have been infected at one event, before the ship got underway, and these are all just cases from a single point source,” which is why an epidemiological investigation is critical. However, “if there are multiple generations of cases, waves of cases, then that makes it more likely that there was human-to-human transmission,” he added.

Seven Cases

The WHO reported that epidemiological investigations are underway to determine the source of exposure. The ship — the MV Hondius, operated by Dutch company Oceanwide Expeditions — was denied permission to dock in Cape Verde in the Canary Islands on Monday. Passengers are isolated in their cabins .

On Monday night, the WHO reported a total of seven cases — two lab-confirmed cases of hantavirus and five suspected cases — including three deaths, one critically ill patient, and three people reporting symptoms. Illness onset began April 6-28 and was characterized by fever, gastrointestinal symptoms, rapid progression to pneumonia, acute respiratory distress syndrome, and shock.

The ship had departed Ushuaia, Argentina, on April 1 with 147 passengers including crew, stopping at several remote islands including the Falkland Islands, the British Overseas Territory of Saint Helena, Ascension Island, and Tristan da Cunha.

According to the WHO and South African health officials, the first patient was a 70-year-old man who died on board on April 11. His 69-year-old wife collapsed at the O.R. Tambo International Airport near Johannesburg, South Africa, and died at a local hospital on April 26. The couple had traveled in South America, including Argentina, before they boarded the ship.

A third patient, a British national, was medically evacuated to South Africa on April 27, where he remains in critical condition and in isolation.

A fourth patient, a woman with pneumonia, died on May 2, with symptoms beginning on April 28.

Three other suspected cases have reported high fever and/or gastrointestinal symptoms and remain on board, where they are being evaluated by medical teams and having additional samples collected for testing.

Other Hantaviruses

Another type of hantavirus that causes cardiopulmonary syndrome is Sin Nombre virus, which is found in North America and is particularly common in the Four Corners region of the U.S. Late actor Gene Hackman’s wife died in 2025 of a hantavirus infection.

Other hantaviruses can cause hemorrhagic fever with renal syndrome (HFRS), including Seoul virus, which is found in wharf rats in port cities around the world, Lawler said.

The virus affecting the cruise ship is unlikely to be Seoul virus, but if it was, it “might change your thought process” in an epidemiological investigation, he added. “There’s not known human-to-human transmission of Seoul virus, so you’d have to think that maybe this was a continuing source that might be on the ship that was infecting multiple people,” such as a rodent infestation, he said.

Hantaviruses are primarily acquired through contact with the urine, feces, or saliva of infected rodents or by touching contaminated surfaces. Symptoms typically occur 2 to 4 weeks after exposure, but may appear as early as 1 week or as late as 8 weeks after exposure, according to WHO.

Mehta said NETEC is disseminating targeted communications to healthcare workers about how to recognize hantavirus infections, how to prepare healthcare staff and hospitals for potentially receiving patients, and how to treat patients. A total of 17 passengers on the ship are American.

Treating Hantavirus

Mehta noted there are 13 facilities in the U.S. that are designated level 1 regional emerging special pathogen treatment centers that can provide highly specialized care, along with dozens of level 2 centers that can care for additional patients. There’s also a national program for monitoring exposed individuals once they return to the U.S., so that they can get appropriate care quickly if needed.

There’s no specific treatment for hantavirus; it’s just best supportive care, Lawler said. It “focuses on keeping folks oxygenated, usually intubating them and putting them on a ventilator.”

“You get heart failure and fluid backing up into the lungs, so if you can put people on positive pressure ventilation and you can support their heart function and try to reduce the impact of the fluid buildup that impedes gas exchange in their lungs, then you can keep the person going until their immune system clears the infection, and their immune dysregulation calms down,” he explained.

The WHO noted that given the rapid progression of hantavirus cardiopulmonary syndrome, “close monitoring and early transfer to ICU are critical for more severe cases.”

There’s no antiviral approved for the condition, WHO said. While ribavirin has shown efficacy against HFRS, it hasn’t shown any effectiveness for hantavirus cardiopulmonary syndrome.

Lawler said that, at this stage, it’s likely the State Department in coordination with the CDC and the Administration for Strategic Preparedness and Response at HHS are starting to plan contingencies for managing exposed or ill Americans.

“It’s helpful to be cautious at this stage, but you also need to make sure that the passengers on board are safe and being taken care of, that anybody needing medical attention is receiving it,” Lawler said. “That’s one of the most important first priorities, then it’s understanding what you’re dealing with.”