A Winnebago County resident has a suspected case of hantavirus. The person is believed to have gotten ill after cleaning a home with rodent droppings in it, which is a different strain than the one affecting cruise ship passengers.

Here’s what you need to know about hantavirus.

What is hantavirus?

Hantavirus is a disease typically spread to humans through rodents and their droppings. The Centers for Disease Control and Prevention says that hantaviruses are “a family of viruses which can cause serious illnesses and death.”

The Andes strain – associated with the Dutch cruise ship MV Hondius, the IDPH said – is the only type of hantavirus that is known to spread person-to-person. But spread is typically limited to people in close contact with the sick person, according to the CDC.

The hantavirus strain most common in the U.S. is caused by exposure to rat droppings and not contagious from person to person, the Illinois Department of Public Health said. The long-tailed pygmy rice rat, known to carry the Andes strain in South America, does not live in the U.S., the IDPH said.

Hantavirus is most likely to occur in rural areas where the deer mouse lives. The deer mouse appears to be the main source of the virus in the U.S.

Hantaviruses cause two syndromes. Hantaviruses found in the Western Hemisphere can cause hantavirus pulmonary syndrome (HPS), according to the CDC.

Hemorrhagic fever with renal syndrome (HFRS) is a group of similar illnesses caused by hantaviruses found mostly in Europe and Asia. However, Seoul virus, a type of hantavirus that causes HFRS, is found worldwide, including in the U.S., according to the CDC.

What are the symptoms of hantavirus?

Symptoms of HPS usually start to show one to eight weeks after contact with an infected rodent.

Early symptoms can include, according to the CDC, can include fatigue, fever and muscle aches, especially in the large muscle groups like the thighs, hips, back and sometimes shoulders.

About half of all HPS patients also experience headaches, dizziness, chills and abdominal problems, like nausea, vomiting, diarrhea and pain.

Four to 10 days after the initial phase of illness, the late symptoms of HPS appear, like coughing and shortness of breath. Patients might experience tightness in the chest, as the lungs fill with fluid.

HPS can be deadly. Thirty-eight percent of people who develop respiratory symptoms may die from the disease.

According to the CDC, HFRS is a severe and sometimes deadly disease that affects the kidneys. Symptoms usually develop within one to two weeks after exposure but, in rare cases, can take up to eight weeks.

Initial symptoms begin suddenly and include intense headaches, back and abdominal pain, fever and chills, nausea and blurred vision. People may have flushing of the face, inflammation or redness of the eyes, or a rash.

Later symptoms can include low blood pressure, lack of blood flow, internal bleeding or acute kidney failure, which can cause severe fluid overload.

The severity of the disease varies depending on the virus causing the infection. Hantaan and Dobrava virus infections usually cause severe symptoms, where 5 to 15% of cases are fatal. But Seoul, Saaremaa and Puumala virus infections are usually less severe, with fewer than 1% dying from the disease. Complete recovery can take several weeks to months.

What is the situation in Illinois?

The IDPH said Tuesday a person in Winnebago County potentially has hantavirus. The IDPH said the person was believed to have gotten a North American strain of the virus while cleaning a home where rodent droppings were present.

That person has not traveled internationally and is not connected to the cruise ship outbreak, the IDPH said, adding the person was not seriously ill and experienced mild symptoms that did not require hospitalization.

“IDPH is working with the CDC on additional testing to confirm the resident is positive for Hantavirus. That process can take up to 10 days, according to the CDC,” IDPH said.

Hantavirus is extremely rare. Illinois has seen seven positive hantavirus cases since 1993, not including the potential new case, the IDPH said. The most recent case was in March 2025.

What is the situation locally?

In DeKalb County, Stacia Runge, director of community health and prevention, said Wednesday there is no hantavirus in the county. The health department only gets notified if someone visits the doctor and gets tested, she said.

Occasionally, someone gets diagnosed with hantavirus after they cleaned their home or camper and came into contact with rodent feces. That strain of hantavirus is not known to spread between people.

If someone with hantavirus from the cruise ship came to DeKalb County and the health department was notified, Runge said “we would go into gear,” like they do for measles – there was a recent measles case in the county – and other diseases.

If a person with hantavirus potentially exposed others, the health department would need to contact every person the person potentially exposed and set up the person for monitoring.

But, all the cruise ship passengers are being held in quarantine facilities elsewhere so Runge didn’t anticipate that happening.

In McHenry County, Department of Health public information officer Nick Kubiak said the health department is monitoring hantavirus. Most cases come from the southwestern region of the country.

The Community & Reportable Disease nurses, epidemiology team and nursing leadership are monitoring CDC and IDPH guidance, Kubiak said.

If a McHenry County resident gets hantavirus, the health department “has established response protocols in coordination with IDPH, the CDC, and local health system partners to support a swift and appropriate public health response.”

How to rodent-proof property

Runge said people cleaning up areas with rodent feces, like basements and garages, should mask up, wear gloves and practice good handwashing. People can vacuum up the fecal matter and come back and clean the area with bleach or other cleaning supplies, Runge said.

Kubiak said, in information he attributed to IDPH: “To keep rodents out of a building, you must create an environment that does not attract them. Deny rodents food, water, nesting sites and entry to the building.”

That includes reducing the availability of food and water, keeping your kitchen clean, storing human and pet food in tightly closed containers, keeping food scraps and garbage in rodent-proof metal or thick plastic containers with tight-fitting lids, storing bulk animal food at least 100 feet from the home in containers with tight-fitting lids and repairing leaky faucets that may provide water to rodents.

Also, eliminate nesting sites near a building and keep your lawn mowed, as tall grass and weeds are excellent habitats for rodents. When possible, place wood piles, compost heaps, feed bins and trash cans at least 100 feet from the home. Wood piles should be at least 12 inches off the ground. Haul away trash, abandoned vehicles, discarded tires and other items that could serve as rodent nesting sites. Place 3 inches of gravel under the base of mobile homes to discourage burrowing by rodents.

Building should be sealed by first identifying all possible sites of rodent entry. A mouse can fit through a hole slightly larger than 1/4 inch. Use steel screen, sheet metal, galvanized hardware cloth, caulk or weather stripping to seal holes or gaps along the edges of windows and entry doors and garage doors. Check places where pipes and electrical wiring enter the house and seal openings with steel wool.