What is hantavirus and how does it spread?

By Christian Edwards, CNN

(CNN) — Hantavirus, a rare disease typically caused by exposure to infected rodents’ urine or feces, is suspected in the deaths of three people after an outbreak aboard a cruise ship in the Atlantic Ocean.

One hantavirus case has been confirmed, according to the World Health Organization (WHO), with five more suspected cases under investigation. The ship had been traveling from Argentina to Cape Verde, a group of island off the coast of West Africa.

At first, hantavirus can feel like the flu, with patients suffering from fatigue, fevers, chills and aches. But over time, as the virus damages the heart, lungs or kidneys, patients can suffer severe shortness of breath, organ failure and even die.

WHO said Monday that there is no need for alarm and that the risk to the wider public remains low. Still, experts are puzzled as to how the disease could have spread on the cruise ship.

Here’s what to know about hantavirus.

What is hantavirus?

Hantavirus refers to a strain of viruses spread by rodents through their bodily fluids and excrement.

Humans often become infected when they inhale particles from dried rodent droppings. Typically, this happens when someone attempts to dispose of rodent droppings by sweeping them up, causing the particles to become airborne. The most common hantavirus in the United States is spread by the deer mouse.

Humans can also become infected by touching contaminated objects and then touching their mouth or nose. Hantavirus can also spread through rodent bites or scratches, though this is rare.

Only one hantavirus – the Andes strain, native to South America – is known to have spread from person-to-person, and this is rare.

What are hantavirus symptoms?

Hantaviruses are the cause of two types of severe illness.

Hantaviruses found in Europe and Asia can cause hemorrhagic fever with renal syndrome (HFRS), which affects the kidneys. What starts with headaches, abdominal pain and nausea can develop into low blood pressure, internal bleeding and acute kidney failure. Between 5-15% of cases are fatal, according to the US Centers for Disease Control and Prevention, and symptoms typically take one to two weeks to develop after exposure.

Hantaviruses found in the Americas cause hantavirus pulmonary syndrome (HPS). This disease, which affects the lungs, also initially causes flulike symptoms. But over time, some patients can experience shortness of breath and tightness in the chest, as the lungs fill with fluid. After exposure, symptoms can take one to eight weeks to develop. Nearly 40% of those who develop respiratory symptoms may die from HPS, the CDC said.

Is there a cure for hantavirus?

There’s no specific treatment for hantavirus, according to the CDC. Patients can be treated with hydration, rest and for specific symptoms.

For that reason, prevention is important. The best way to protect yourself from hantavirus, the CDC says, is to keep rodents out of your home – by sealing any gaps or holes in your home, keeping food well sealed and putting garbage in thick containers with tight lids.

When cleaning rodent droppings, use gloves, spray the waste with a bleach solution and wait for five minutes, before wiping the area with paper towels and disposing of them safely.

How common is hantavirus?

There are an estimated 60,000 to 100,000 cases of HFRS worldwide each year, with China accounting for about half of the cases, according to a 2024 study.

From 1993 to 2023, 890 cases of hantavirus disease had been reported in the US, most of them in western states, CDC data shows.

Interest spiked in the little-known disease last year, after Betsy Arakawa, the wife of the Oscar-winning actor Gene Hackman, died from HPS at age 65. Local public health records obtained by CNN revealed findings of dead rodents and rodent nests throughout several detached outbuildings on the couple’s property in New Mexico.

It is believed that Arakawa died around a week before her husband, who was in the advanced stages of Alzheimer’s disease.

How did this outbreak occur?

We don’t yet know. Dr. Charlotte Hammer, an assistant professor and epidemiologist at the University of Cambridge, said there were multiple possible scenarios.

“It is not entirely uncommon for rodents to hitch a ride on a ship, which could be one possibility,” Hammer said.

Because the incubation period for the disease is one to eight weeks, it is also possible that people could have become infected when the ship last made port in Argentina, Hammer added. Another possibility would be “human-to-human transmission,” which she said would be “very unlikely” at this scale.

To find out how the disease spread on board, Dr. Scott Miscovich, family physician and the president and CEO of Premier Medical Group, said the ship needs to be “cultured to the max,” referring to the process of incubating viruses to identify them.

“All the droplets, all the dust in every room, all the kitchens, all the ventilation systems need to be sampled and then cultured,” he said.

The World Health Organization said detailed investigations are underway, including sequencing of the virus.

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CNN’s Ally Barnard, Issy Ronald and Lex Harvey contributed reporting.