Hantavirus With Human-to-Human Spread Suspected in Deadly Cruise Ship Outbreak

Infectious disease experts believe a rare type of hantavirus known as Andes virus may be behind an outbreak aboard a small cruise ship that has already killed three people and possibly infected at least four others. This virus, which causes a severe lung and heart condition called hantavirus cardiopulmonary syndrome, is found in Argentina and other South American countries and has a documented ability to spread 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,” said Dr. James Lawler, an infectious disease expert at the University of Nebraska Medical Center’s Global Center for Health Security in Omaha.

Dr. Aneesh Mehta of Emory University in Atlanta and the National Emerging Special Pathogens Training and Education Center (NETEC) agreed that Andes virus is a strong possibility given the number of severe cases and the fact that the cruise originated in Argentina. He warned that this raises concerns about the virus spreading more broadly.

“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 said.

A previous outbreak of Andes virus in Argentina from November 2018 through February 2019 caused 34 confirmed infections and 11 deaths, according to a report in the New England Journal of Medicine. In that outbreak, the virus jumped from a rodent into a single person, and then spread further when three symptomatic people attended crowded social events. That strain was similar to the one involved in the first documented human-to-human transmission of Andes virus, which happened in Argentina in 1996. Several other instances of person-to-person spread have been reported, mostly in Argentina but also in Chile.

Lawler noted that it is possible all the cruise ship passengers “could have been infected at one event, before the ship got underway, and these are all just cases from a single point source.” That is why an epidemiological investigation is so important. “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.

The World Health Organization (WHO) reported that epidemiological investigations are underway to find 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 currently isolated in their cabins.

As of Monday night, the WHO reported a total of seven cases: two lab-confirmed cases of hantavirus and five suspected cases. That includes three deaths, one critically ill patient, and three people with symptoms. Illness onset began between April 6 and April 28, with symptoms including fever, stomach and intestinal problems, rapid progression to pneumonia, acute respiratory distress syndrome, and shock.

The ship left Ushuaia, Argentina, on April 1 with 147 passengers and crew. It stopped at several remote islands, including the Falkland Islands, 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 boarding the ship.

A third patient, a British national, was medically evacuated to South Africa on April 27 and remains in critical condition in isolation. A fourth patient, a woman with pneumonia, died on May 2 after symptoms began on April 28. Three other suspected cases have reported high fever and/or stomach and intestinal symptoms. They remain on board, where medical teams are evaluating them and collecting additional samples for testing.

Another type of hantavirus that causes cardiopulmonary syndrome is Sin Nombre virus, found in North America and especially 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 a different illness called hemorrhagic fever with renal syndrome (HFRS). One example is 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.

People usually catch hantaviruses by contact with the urine, feces, or saliva of infected rodents, or by touching contaminated surfaces. Symptoms typically appear 2 to 4 weeks after exposure, but can show up as early as 1 week or as late as 8 weeks, according to the WHO.

Mehta said NETEC is sending targeted messages to healthcare workers about how to recognize hantavirus infections, prepare hospitals for potential patients, and treat those who are sick. A total of 17 passengers on the ship are American. Mehta noted that there are 13 level 1 regional emerging special pathogen treatment centers in the U.S. that can provide highly specialized care, along with dozens of level 2 centers. There is also a national program to monitor exposed people once they return to the U.S., so they can get appropriate care quickly if needed.

There is no specific treatment for hantavirus — only supportive care, Lawler said. That care “focuses on keeping folks oxygenated, usually intubating them and putting them on a ventilator.” He explained that patients experience heart failure and fluid backing up into the lungs. “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.”

The WHO noted that because hantavirus cardiopulmonary syndrome progresses so quickly, “close monitoring and early transfer to ICU are critical for more severe cases.” There is no antiviral approved for the condition. While the drug ribavirin has shown effectiveness against HFRS, it has not worked for hantavirus cardiopulmonary syndrome.

Lawler said that at this stage, it is likely the State Department, working with the CDC and the Administration for Strategic Preparedness and Response at HHS, is starting to plan 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.”

Source: MedPage Today