By Susan Montoya Bryan

An outbreak aboard a cruise ship of a rare rodent-borne illness called hantavirus has left three passengers dead and sickened others, but global health officials say the risk to the general public remains low because the germ does not easily spread between people.

“This is not the next COVID, but it is a serious infectious disease,” said Maria Van Kerkhove, director of epidemic and pandemic preparedness at the World Health Organization. “Most people will never be exposed to this.”

The virus usually spreads when people inhale contaminated residue of rodent droppings. Hantaviruses have been around for centuries and are thought to exist around the world.

The disease gained renewed attention last year after the late actor Gene Hackman ’s wife, Betsy Arakawa, died from a hantavirus infection in New Mexico.

The WHO said detailed investigations of the cruise ship outbreak are ongoing, including further laboratory testing and other work aimed at determining the source of exposure.

Two officials in Argentina said on condition of anonymity because they were not authorized to brief the media — that investigators suspect that the cases were initially contracted during a birdwatching trip in Ushuaia, at the country’s southern tip. However, there’s one big hole in the theory.

Officials have found evidence of Andes virus, a version of hantavirus found in South America.

The virus is spread by rodents and, more rarely, people

Hantavirus is mainly spread by contact with rodents or their urine, saliva or droppings, particularly when the material is disturbed and becomes airborne, posing a risk of inhalation.

People are typically exposed to hantavirus around their homes, cabins or sheds, especially when cleaning enclosed spaces with little ventilation or exploring areas with mouse droppings.

The Andes virus is a concerning member of the hantavirus family

The word hantavirus refers to a broad family of viruses, with different versions in different countries. Almost none of them have been found to spread from person to person — with the possible exception of the Andes virus, which has been confirmed in the current outbreak.

Still, transmission between people does not happen easily, and would require “close and prolonged’’ contact, according to the WHO.

“We haven’t had huge person-to-person spreads of hantavirus infection ever before, and there’s no reason to suspect a huge outbreak from this case at this point,” said Steven Bradfute, an associate professor and associate director of the Center for Global Health at the University of New Mexico Health Sciences Center, which specializes in hantavirus research.

Infections have been relatively uncommon

Hantavirus infections are relatively uncommon globally. The WHO reported that in 2025, eight countries within the Americas had documented 229 cases and 59 deaths. In Argentina, the health ministry said hantavirus led to 28 deaths nationwide last year.

In the U.S., federal health officials began tracking the virus after a 1993 outbreak in the Four Corners region — the area where Arizona, Colorado, New Mexico and Utah meet. It was an astute physician with the Indian Health Service who first noticed a pattern of deaths among young patients.

Most U.S. cases are in Western states. New Mexico and Arizona are hot spots, likely because the odds are greater for mouse-human encounters in rural areas.

The illness starts with flu-like symptoms

An infection can rapidly progress and become life-threatening. Experts say it can start with symptoms including fever, chills, muscle aches and maybe a headache — much like the flu.

Symptoms of hantavirus pulmonary syndrome usually show between one and eight weeks after contact with an infected rodent. As the infection progresses, patients might experience tightness in the chest, as the lungs fill with fluid.

The other syndrome caused by hantavirus — known as hemorrhagic fever with renal syndrome, which can cause bleeding, high fever, and kidney failure — usually develops within a week or two after exposure.

Death rates vary by which hantavirus causes the illness. Hantavirus pulmonary syndrome is fatal in about 35% of people infected, while the death rate for hemorrhagic fever with renal syndrome varies from 1% to 15% of patients, according to the CDC.

A lot of unknowns about the illness and treatment

There is no specific treatment or cure, but early medical attention can increase the chance of survival.

Despite years of research, many questions have yet to be answered, including why it can be mild for some people and severe for others and how antibodies are developed. Some researchers have been following patients over long periods of time in hopes of finding a treatment.

“In the Americas, hantavirus infection is very serious, but it’s also quite rare,” Bradfute said. “And so for a time that probably led to less research into it because of funding priorities, but I know there’s been a lot of interest in funding hantavirus work of late.”

What researchers do know is that rodent exposure is key.

The best way to avoid the germ is to minimize contact with rodents and their droppings. Use protective gloves and a bleach solution for cleaning up rodent droppings. Public health experts caution against sweeping or vacuuming, which can cause virus particles to get into the air.