U.S. Monitors Hantavirus Spread After Deadly Cruise Ship Outbreak

As investigations continue into the hantavirus outbreak that originated on the expedition cruise ship MV Hondius, health officials across the United States are taking precautionary measures to monitor potential cases.

The outbreak, which began during a voyage from Argentina across the Atlantic, has resulted in three deaths and at least eight reported cases, several laboratory-confirmed according to the World Health Organization and subsequent health reports.

At least five states—Texas, Virginia, Georgia, Arizona and California—are now monitoring residents who returned from the affected vessel, according to recent reports.

The current cruise ship outbreak reportedly originated with a couple who contracted the virus while traveling in Argentina. “They were not symptomatic at all—the incubation period can be one, two, three or four weeks,” explained Dr. Luis Marcos, professor of medicine and director of the Infectious Diseases Fellowship Program at Stony Brook Medicine in New York.

Hantavirus in the United States

Historical data shows approximately 800 to 900 cases of hantavirus have been recorded in the United States. The Centers for Disease Control and Prevention (CDC) confirms that 890 cases of hantavirus disease were reported in the U.S. from 1993 through the end of 2023.

“Most of these cases have been west of the Mississippi River, and classically the risk factors are being in contact with feces and urine from rodents,” Dr. Marcos told Fox News Digital.

The most common strain in the U.S. is called Sin Nombre, which differs from the current outbreak strain. Unlike the Andean strain implicated in the cruise ship cases, the Sin Nombre variant is not transmitted from human to human.

“The only proven human-to-human transmission has been with the Andean virus from South America—and that’s what’s happening now,” Dr. Marcos explained.

Transmission and Symptoms

Most hantavirus strains spread when people inhale contaminated particles from rodent urine, droppings or saliva. Less commonly, infection can occur from touching contaminated surfaces and then touching the mouth, nose or eyes.

Typical exposure scenarios involve people who have been camping or hiking in remote areas and were inadvertently in contact with rodent waste. In contrast, the current outbreak aboard the cruise ship represents a rare case of human-to-human transmission.

Most infected individuals develop flu-like symptoms including fever and muscle pain. “Some people may have mild disease, so not everybody will be very, very sick,” Dr. Marcos noted.

In rare cases, hantavirus can progress to hantavirus pulmonary syndrome (HPS), a serious condition where the lungs fill with fluid. “The mortality rate [among those with HPS] is between 30% and 60%—so yes, it’s a deadly virus,” Dr. Marcos added.

Quarantine and Risk Assessment

The virus has an unusually long incubation period, which necessitates an extended quarantine for those potentially exposed. “The longest incubation period has been 56 days or so, so two months, roughly,” Dr. Marcos explained. “But most cases will get sick within two to three weeks.”

Regarding transmission risk, Dr. Marcos emphasized that those at highest risk are people in “close contact,” typically meaning living in the same environment where fluids can be exchanged.

“It has to be really, really close contact,” he said. “The transmission is not as efficient as other viruses.” While airborne transmission via droplets is possible, it is “not as effective” as COVID, influenza or cold viruses.

Treatment and Prevention

Currently, there are no specific antiviral treatments for hantavirus. “What happens is the patient will end up in the hospital. We will do supportive care, which means if your lungs are full of fluid, you will require a ventilator until the virus runs its course,” Dr. Marcos explained.

Although there is currently no vaccine for hantavirus in the U.S., several are in development.

Despite the concerning nature of the cruise ship outbreak, Dr. Marcos believes the risk of hantavirus leading to a pandemic is “pretty much almost zero.”

“I don’t feel a strong risk of a pandemic,” he told Fox News Digital. “The transmission is not like COVID. It’s very different. I really think this is going to go away in the next two to three weeks, and we will know exactly the number of cases.”

To prevent hantavirus infection, health experts recommend wearing gloves and a mask in environments where rodents might be present, such as when cleaning basements or other enclosed spaces. Proper ventilation and frequent hand-washing are also essential preventive measures.