Officials say further testing has confirmed that a potential case of hantavirus in a resident living in northern Illinois was a false positive following reports last week that it could be the first case in the state.
The Illinois Department of Public Health (IDPH) said in a statement on Tuesday that it was investigating the first potential hantavirus case in an Illinois resident.
The case was not believed to be connected to the recent outbreak on the MV Hondius cruise ship.
The resident lives in Winnebago County, has not travelled internationally and has not come in contact with individuals associated with the MV Hondius outbreak, according to the IDPH.
They were suspected of having acquired a North American strain of the virus while cleaning a home where rodent droppings were present.
The North American strains of hantavirus are not known to spread from person to person, unlike the Andes strain of hantavirus responsible for the cruise outbreak.
The risk of contracting hantavirus of any kind remains very low for Illinois residents, IDPH said.
The Illinois resident was not seriously ill and was recovering after experiencing mild symptoms that did not require hospitalization.
The IDPH said they began working with the CDC on additional testing to confirm whether the resident was positive for hantavirus.
The agency said in an update on Monday that the confirmatory testing by the CDC showed the resident was negative for hantavirus and it was a false alarm.
“The resident is no longer considered a potential case of Hantavirus and no further public health action is needed,” an IDPH spokesperson said Monday.
Commercial lab serology or antibody tests, which the individual received, are not considered definitive and require confirmation by a more sensitive test at the CDC, which ended up ruling out the virus.
The IDPH said the best way for people to protect themselves from Hantavirus and other rodent-borne diseases is by keeping rodents out of their homes and cleaning up after them safely.
Illinois has had seven positive cases of Hantavirus since 1993, most recently in March 2025, prior to the most recent case.
The U.S. has recorded 890 cases of hantavirus over 30 years since surveillance began in 1993.
The hantavirus strain most commonly seen in the U.S. is caused by exposure to rodent droppings and is not contagious from person to person, the IDPH said.
The rodent species — long-tailed pygmy rice rat — known to carry the Andes strain of the virus in South America does not live in the U.S.
The CDC contacted states that had residents aboard the cruise ship connected to the hantavirus outbreak but Illinois has not received communication from the CDC.