Monitoring hantavirus amid global concern

Six years after the start of the COVID-19 pandemic, health officials worldwide are now trying to provide reassurance about a different virus: Andes virus, a type of Hantavirus.

These are a family of viruses that carried primarily by rodents and can be transmitted from rodents to humans.

While human-to-human spread doesn’t happen often, it can cause severe illness when it does occur. Sharjeel Ahmad, MD, a staff physician of infectious disease with OSF HealthCare, says there’s one major health concern to stay aware of.

"In the Americas, hantaviruses cause the hantavirus cardiopulmonary syndrome (HCPS). It's a disease characterized primarily by rapid onset failure of breathing (respiratory failure), and heart problems (cardiovascular shock)," Dr. Ahmad says. "The current strain in the news is the Andes virus strain, which is linked to a cluster of passengers onboard a cruise ship, the MV Hondius, which traveled to Patagonia in South America."

Hantavirus is spread through infectious particles that are aerosolized (spreading throughout the air), infected urine, feces or saliva, especially when the contaminated dust becomes airborne during cleaning. That's why Dr. Ahmad stresses that it’s so important for house cleaners or those who may come across rodents or their droppings to be even more cautious. 

The animal reported to have been the reservoir of the Andes strain was a long-tailed pygmy rice rat, Dr. Ahmad says. It’s a rodent found in rural areas of central and southern Chile and the southern Andean region of Argentina.

The cruise ship itself wasn't the only reason it became a nest for the hantavirus to spread, Dr. Ahmad says. But it was also impacted by how passengers picked it up in the first place.

"It creates a unique convergence of risk factors," he says. "Passengers likely had direct environmental exposure to rodent habitats during an shore excursions where the virus is in the endemic stage. Things like hiking, visiting rural structures and exploring the wilderness where infected rodents may be."

Unlike COVID-19, influenza or other well-known viruses, hantavirus does not spread through brief interactions between people.

There's prolonged exposure between people, and infected individuals share rooms with their friends or family members. Medical access on a cruise ship also becomes a point that makes the situation more difficult. 

"Sharing a bed, kissing, attending social gatherings and spending time in close quarters," are common ways viruses like this spread, Dr. Ahmad points out.  

The incubation period for the Andes strain is very long, anywhere from seven to 49 days. This means that people with the virus could have been exposed on shore and not developed symptoms until days or weeks later. 

One hantavirus case is currently being investigated in Illinois, but it has no connection to the cruise ship outbreak. On Monday, May 18, 2026, the Illinois Department of Public Health (IDPH) reported that the Centers for Disease Control and Prevention (CDC) conducted a confirmatory test on the person which turned out to be negative.

In the U.S., 30-40 cases of hantavirus happen each year, normally in the rural parts of Western and Southwestern America like Utah, Colorado, New Mexico and Arizona. Since surveillance began in 1993, the U.S. has recorded 890 cases. This shows that public burden in America remains very low.

Dr. Ahmad says COVID-19 was much more efficient at spreading through respiratory droplets.

The HCPS mortality rate is high. Dr. Ahmad says it’s roughly 35-40% in the United States for several reasons, including the virus’ ability to rapidly cause severe lung fluid leakage and heart dysfunction leading to respiratory failure and shock within hours. Additionally, there are no specific antiviral treatments or vaccines available for hantavirus. 

"This virus targets the lining of the blood vessels, called the endothelium, and causes them to become leaky. So, you get this fluid, it leaks into the lungs and then the heart dysfunction happens," Dr. Ahmad says. "So, both your lungs and heart are not working well." 

However, he believes that hantavirus cases are likely underreported, and that is why the mortality rate is so high. 

“The treatment is entirely supportive care, including admission to the intensive care unit for careful monitoring, careful fluid management, and medication to support blood pressure and the heart,” Dr. Ahmad adds. “Some people may need a ventilator for respiratory failure. In rare cases, someone severely ill may need extracorporeal membrane oxygenation (ECMO), which is in essence is a heart-lung bypass machine.”

Progression of illness from flu-like symptoms to critical access is very fast, Dr. Ahmad says. "Most of it happens within the first 24 hours." 

The best chance of survival, Dr. Ahmad adds, is catching the disease early and getting treatment as soon as possible. Other tips include:

-       Seal homes and buildings: Close gaps and holes where rodents can enter - around pipes, vents, doors, and foundations.

-       Eliminate food sources: Store food in sealed containers, clean up spills, and secure garbage.

-       Clean safely: Don’t sweep or vacuum rodent droppings dry. Ventilate the area, spray droppings/nesting material with disinfectant or diluted bleach, let it soak, then wipe up with gloves.

Dr. Ahmad says it’s additionally important to keep this illness in mind if you’re traveling somewhere where Hantavirus is in the endemic (native to, or constantly present) stage, like Patagonia, and take common sense measures to prevent exposure.

Infectious disease specialists understand this virus well, Dr. Ahmad reassures, which is why he does not believe there is any chance of a pandemic from this hantavirus strain. 

"Stay informed, avoid panic and focus on practical prevention," he recommends. 

As of May 18, 2026, there were 41 people across the U.S. being monitored for hantavirus. Over the prior weekend, a person in Canada who was on the cruise ship was reported to test positive for the virus.

The CDC is working with state and federal partners to monitor passengers who were on the affected cruise ship. Certain sick patients have been treated at the Nebraska Biocontainment Unit in Omaha and Emory University Hospital in Atlanta. The two patients being monitored in Atlanta were discharged on Friday, May 15 from the hospital’s Serious Communicable Disease Unit. They have now been moved to the Nebraska Biocontainment Unit to join the 16 others.

The World Health Organization (WHO) Director-General, Tedros Adhanom Ghebreyesus, continues to say the risk to the global population remains low.

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