Andes Hantavirus Outbreak on Cruise Ship: WHO Confirms Human-to-Human Transmission, Three Dead
Key Insights
The WHO confirmed the Andes virus, a hantavirus (search) capable of human-to-human transmission, is responsible for the outbreak aboard the MV Hondius cruise ship that killed three people.
Five laboratory-confirmed cases and three additional suspected cases have been reported, with California residents among the 147 passengers and staff on board.
Officials emphasize the risk to the general public is "extremely low," as transmission requires close and prolonged contact, and the virus does not spread like SARS-CoV-2.
Some California residents were among the 147 passengers and staff aboard a luxury cruise ship stricken by a suspected outbreak of hantavirus (search) that has left three people dead and several others severely ill, officials confirmed Thursday. The World Health Organization has identified the Andes virus — a form of hantavirus capable of human-to-human transmission — as the pathogen responsible for the outbreak aboard the Dutch-flagged MV Hondius.
California public health officials say they are monitoring the situation after being notified by the U.S. Centers for Disease Control and Prevention (search) that some state residents were passengers on the vessel. The precise status of those individuals, however, remains murky.
Outbreak Origin and Transmission Dynamics
The MV Hondius was on a 46-day journey that traveled from Antarctica with stops in Argentina. On April 1, 114 guests boarded the cruise ship in Ushuaia, Argentina. The first passenger to have been infected, a Dutchman, became sick aboard the cruise ship on April 6 and died on April 11. No samples were taken because his symptoms were similar to other respiratory diseases.
His widow left the ship with his body on April 24 during a scheduled stop at St. Helena, a remote island about 1,100 miles off the coast of Africa. "She deteriorated during a flight to Johannesburg on the 25th of April and died the next day," said Dr. Tedros Adhanom Ghebreyesus, director-general of the WHO.
Before boarding the cruise ship, the Dutch couple had traveled through Argentina, Chile and Uruguay on a bird-watching trip, "which included visits to sites where the species of rat that is known to carry Andes virus was present," Tedros said.
Dr. Gaby Frank, director of the Johns Hopkins Special Pathogens Center, explained that in the case of human-to-human transmission, a person would first be infected by a wild rodent's contaminated particles and then pass the infection to someone else.
"In previous outbreaks of Andes virus, transmission between people has been associated with close and prolonged contact, particularly among household members, intimate partners and people providing medical care," Ghebreyesus said. "That appears to be the case in the current situation."
Case Count and Monitoring
The number of lab-confirmed hantavirus (search) cases has risen to five, according to the WHO, with three additional suspected cases. The WHO is monitoring reports of other people with symptoms "who may have had contact with one of the passengers. In each case, we are in close contact with the relevant authorities," Tedros said.
None of the remaining passengers or crew members on the ship are symptomatic, he confirmed. The ship was not permitted to allow passengers to disembark at its original destination, Cape Verde, and is sailing for Spain's Canary Islands.
On April 24, 30 passengers — including six people from the United States — disembarked at St. Helena. Public health agencies in California, Georgia and Arizona were notified by the CDC that some of their residents were among the passengers on the cruise. It remains unclear whether these individuals disembarked on April 24.
As of Friday, one passenger has returned to their California residence and is in contact with local public health officials, and at least one other remains aboard the ship, according to the California Department of Public Health.
Risk Assessment and Public Health Response
"I want to be unequivocal here: This is not SARS-CoV-2. This is not the start of a COVID pandemic. This is an outbreak that we see on a ship. There's a confined area," said Dr. Maria Van Kerkhove, who leads the WHO's epidemic and pandemic management. "This is not the same situation we were in six years ago. It doesn't spread the same way like coronaviruses do."
Dr. Erica Pan, director of the California Department of Public Health, echoed this assessment: "Unlike influenza and COVID-19, years of experience in South America have shown that this Andes hantavirus (search) rarely spreads between people."
The current public health protocol involves daily symptom monitoring and reporting. "As there are no known cases of Andes hantavirus (search) infection from people without symptoms, and any spread has usually been limited to people with prolonged close contact with an ill person with this virus, the risk to the general public in California is extremely low," the agency said in a statement. The CDC also stated that the risk to the American public "is extremely low" at this time.
More cases may be reported, because the incubation period for the Andes strain of the hantavirus (search) is up to six weeks.
Clinical Features and Disease Burden
Hantavirus (search) is a rare but deadly disease that attacks the lungs and is typically contracted by humans through inhalation of particles contaminated with the urine, feces or saliva of a wild rodent. There are roughly 50 identified species of hantavirus. The virus found in the Americas tends to cause a cardiopulmonary syndrome, a condition that affects the heart and the lungs, according to Dr. Frank.
Early symptoms of hantavirus (search) are similar to the flu and include fatigue, fever and muscle aches, according to the CDC. Symptoms start to develop within one to eight weeks after contact with an infected rodent. Half of those who contract the virus also experience headaches, dizziness, chills, nausea, vomiting, diarrhea and abdominal pain. Four to 10 days after the initial phase of the illness, another round of symptoms can develop, which include coughing, shortness of breath and possible tightness in the chest as the lungs fill with fluid.
CDC officials said 38% of people who develop respiratory symptoms may die from the disease. There have been 890 laboratory-confirmed cases of hantavirus (search) disease reported in the U.S. since surveillance began in 1993. From 1980 to 2025, 99 California residents have been diagnosed with a hantavirus infection.
There is no vaccine or specific antiviral medicine for hantavirus (search). Intensive-care treatment may include intubation and oxygen therapy, fluid replacement and use of medications to lower blood pressure, according to the American Lung Association.
Flight Attendant Investigation
Dutch news outlets reported that a flight attendant on a KLM airplane — who briefly had contact with the widow of the index patient — started feeling sick and had mild symptoms and was in isolation at a hospital in Amsterdam. The flight attendant has since tested negative for the Andes virus, according to Dr. Jeremy Faust, an emergency medicine physician, citing a text message sent to him by Tedros.
"It is still possible that the flight attendant contracted the Andes virus. However, given our understanding of the virus, this information means that the flight attendant's symptoms are not caused by the Andes hantavirus (search), but by some other medical illness," Faust wrote.
Argentine Investigation
Weeks later in Argentina, from where the hantavirus (search)-stricken cruise set sail, authorities are still trying to figure out the origin of the outbreak. An early hypothesis suggested that patient zero, a Dutch ornithologist, may have become infected in Ushuaia. But Argentine scientists who tested rats for the Andes hantavirus (search) in the area recently ruled out Ushuaia as the source of the outbreak. Argentina also concluded the wine-producing province of Mendoza was not the source of contagion, after local investigators and biologists from the U.S. CDC found no trace of hantavirus in rodents collected from areas visited by the Dutch man and his wife.