Three Washington residents were exposed to hantavirus amid the cruise outbreak. Why risk of further spread is low

May 13-Six years ago, scenes of an infected cruise ship were one of the earliest signs of a worldwide pandemic. History is not likely to be repeated with a recent ship overrun with hantavirus.

Hantavirus is more difficult to spread than COVID-19, and human-to-human transmission does not occur in the hantavirus strain typically found in the United States. Spread of hantavirus aboard the cruise ship, however, originates from the Andes strain. Even with the Andes strain, human-to-human transmission is difficult.

"Transmission potential in hantavirus is extremely low, extremely rare, and is limited to prolonged, very close contact with someone that is ill," Spokane Health Officer Dr. Francisco Velázquez said of the Andes strain.

The outbreak of the virus aboard the cruise ship sailing across the Atlantic from Argentina has captivated the world in recent weeks. There have been three deaths and at least 10 cases connected to the ship. Passengers were evacuated and remain in quarantine in their respective countries, including 18 Americans.

One of those passengers is a King County resident who is currently asymptomatic and being monitored with other hantavirus-exposed Americans at a quarantine center in Nebraska.

Two other King County residents were exposed to the virus because they sat on an airplane near an ill cruise ship passenger who was removed before takeoff and later tested positive for hantavirus. They are also asymptomatic and being monitored at their Seattle-area residence.

King County Health Officer Dr. Sandra Valenciano said the risk of any of the three individuals spreading the virus further is "low at this time."

"I know the current news about hantavirus may be scary," she said in a statement. "Even though these individuals do not show signs of illness, we have strong contact tracing and monitoring in place."

Velázquez agrees that the risk of any kind of widespread outbreak based on these exposures is "extremely low."

"Everybody remembers cruise ships, and everybody remembers people being flown to places for isolation," Velázquez told The Spokesman-Review. "That's why the question of COVID-19 comes up. But the comparison doesn't make sense."

While COVID-19 is a novel virus that took time to figure out, hantavirus has been studied for decades and has a much lower rate of mutation.

"COVID-19 was highly contagious, and it required minimal exposure, minimal time and minimal contact. That's why I try not to compare them," Velázquez said.

What is hantavirus?

The infection is spread by different species of rodents through their urine, saliva and droppings. Mice and other animals carrying the disease typically do not get sick , but humans are at high risk of death if they contract hantavirus.

Different strains are found on every continent except Australia and Antarctica. Strains found in Europe and Asia typically cause less severe symptoms than those found in the Americas.

Hantavirus infection is much rarer than coronavirus or the flu because human-to-human transmission has only been observed in one strain of the disease that is only found in South America. The Andes hantavirus strain is spread by the long-tailed pygmy rice rat, which is only found in Chile and parts of Argentina.

The dominant form of hantavirus in North America is the Sin Nombre strain, which is spread by the deer mouse. There are no documented cases of human-to-human transmission of Sin Nombre hantavirus.

Since surveillance of the virus began in 1993, there have been 890 cases of hantavirus reported in the United States. Most cases originate in western states where the deer mouse most commonly lives. There have been 61 cases of hantavirus in Washington state since 1993. Twenty of those Washington residents have died from the disease after contracting the virus. Five or fewer cases of the virus are reported in Washington each year.

Two cases of the disease have been documented in Spokane County. An individual who contracted the disease in 2024 recovered, but a man in 2017 died from complications related to his hantavirus infection. Even though the man lived in Spokane County, he likely contracted the disease from a barn in Adams County.

Early symptoms of hantavirus can be similar to the flu, including aches and pains, high fever, and fatigue. These early symptoms will develop into Hantavirus Pulmonary Syndrome, which causes intense coughing, difficulty breathing and low blood pressure. These symptoms can cause fatality in 30-50% of cases.

There is not specific treatment for the disease or a vaccine to prevent infection. But early hospitalization can save lives, Velázquez noted.

"Supportive treatment can provide some relief and may mitigate the potential for negative outcome in the patient," he said. "If you feel you may have been exposed, the moment you start to develop symptoms, contact your provider, because most patients require more significant support in a hospital."

It is often difficult to diagnose hantavirus because symptoms often do not arrive for up to six weeks after an exposure.

Hantavirus precautions

Hantavirus most commonly occurs when mouse nests are disturbed during removal. If deer mouse droppings have been left for an extended period, then accumulated dust on the droppings may be stirred up into the air where it can be inhaled.

These factors make rural buildings that remain unoccupied for many months of the year perfect incubators to infect someone when it comes time for spring cleaning. Velázquez recommends caution while cleaning barns, sheds, cabins, garages or storage facilities where mice may have nested over the winter.

"This could be more relevant now because in the spring people are going to open up stuff they are going to be using for the summer," he said. "As long as you are following precautions, the risk of contracting it is very low."

Those precautions include wearing a mask or respirator, gloves and long sleeves while cleaning mouse droppings or an area where mice may have been nesting. Wet down the droppings with a bleach cleaning solution before moving it and avoid using a broom or leaf blower. Once everything is soaked for 10 minutes, remove all of the nest material, mice or droppings with a damp towel and then mop, sponge or wipe down the area with the bleach solution.

"We are trying to keep anything from becoming airborne," Velázquez said.

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This story was originally published May 14, 2026 at 8:08 AM.