Federal health officials continue to monitor 18 American passengers following a hantavirus outbreak aboard the MV Hondius cruise ship that sailed across the Atlantic.

The investigation has prompted questions about where else the virus might be encountered in the United States.

Experts are particularly concerned about the Andes strain, the rare variety linked to the outbreak.

It is the only known hantavirus capable of spreading from person to person, typically after prolonged close contact with an infected individual.

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Dr. Linda Yancey, an infectious disease specialist at Memorial Hermann in the Houston area, noted that most hantavirus cases in the U.S. occur in the desert Southwest and along the West Coast. She said that in Texas, infections are typically found in the western part of the state.

The Bayou strain, native to east Texas and west Louisiana, is less infectious to humans compared to the western Sin Nombre strain, she explained. Different regions face varying risk levels depending on local rodent populations.

According to the Centers for Disease Control and Prevention, hantavirus is mainly transmitted through contact with infected rodents such as deer mice and their urine, droppings, or saliva.

People can become ill after breathing in contaminated dust particles or touching contaminated surfaces and then touching their nose or mouth.

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Rodent bites are a less common but possible route of transmission.

The danger increases when cleaning enclosed or poorly ventilated spaces where rodents may have been nesting for long periods.

Health officials warn that garages, sheds, cabins, attics, barns, and crawl spaces can harbor rodents unseen for weeks or months. Storage units, stables, kitchen cabinets, and spaces behind appliances can also pose exposure risk when rodents are present.

Vehicles that have been left unused, including cars, RVs, campers, and boats, may become habitats for rodents, making reopening them another potential source of exposure.

The National Park Service notes that many human cases emerge in the spring after winter rodent infestations.

Dr. Yancey said that cleaning such areas is one of the most common scenarios for exposure.

“You can be exposed by just the dust and droppings left behind by rodents,” she said. “You don’t even need to see the rodent to be exposed.”

The risk increases when opening unused buildings, sweeping floors, or unpacking boxes covered in dust. Stirring up contaminated materials can send viral particles into the air, experts caution.

People may also encounter the virus while handling firewood, disturbing rodent nests outdoors, or working in areas known to host rodent populations. Public health officials emphasize that seemingly ordinary spaces can present unexpected risks.

Dr. Yancey recommends wearing a mask and wetting down dust or debris with a diluted bleach solution before cleaning.

“This will help kill the exposed virus and reduce the amount of infectious dust,” she advised.

The CDC warns against vacuuming or sweeping rodent droppings, urine, or nesting materials because these actions can spread the virus into the air.

Instead, gloves should be worn, droppings soaked with disinfectant, and the area wiped clean with paper towels.

After cleaning, waste should be properly disposed of, and hands should be washed thoroughly.

Officials say signs of rodent activity include droppings, shredded materials, gnaw marks, musky odors, and scratching sounds in walls or ceilings.

Fox News senior medical analyst Dr. Marc Siegel said that while hantavirus has sparked widespread concern, it remains exceedingly rare in the United States. “It is very rare in the U.S. and is seen out west, but rarely,” he said.

“We need to avoid overpersonalizing the risk of a very rare virus.”