Wisconsin officials are investigating a mysterious blood-borne illness that has infected 44 people and possibly killed 18 in the past few months, NBC reports.
And State Health Officer Karen McKeown says in a statement that officials are expecting more infections.
The bacteria called Elizabethkingia anophelis infect the bloodstream, Newsweek says. Most of the infections involve people older than 65 years in southern part of the state.
The Wisconsin Department of Health Services notes that everyone who has caught it has had at least one serious underlying illness.
So far, 18 people who tested positive for the infection have died. But health officials say they're not sure if it was the infection or an underlying condition that killed them.
Health officials are testing water, skin care products and over-the-counter medications to try to find a source, according to the Wisconsin State Journal.
A state officer tells the paper they have not found any common themes that could lead them to a source, yet. Meanwhile, a director with the Centers for Disease Control described the bacteria as "a difficult one."
Chris Braden with the CDC told the Milwaukee Journal Sentinel that the infection is so rare there aren't national records on how often people get sick or die from it.
The Wisconsin outbreak is the largest there has ever been, the Wisconsin State Journal says.
It's been reported in 11 counties: Columbia, Dane, Dodge, Fond du Lac, Jefferson, Milwaukee, Ozaukee, Racine, Sauk, Washington and Waukesha.
WKOW reports that the infection is treated with antibiotics if it's caught in time. The bacteria are resistant to some antibiotics though.
Signs and symptoms of the disease include fever, shortness of breath, fever, chills or cellulitis.
So far, the outbreak has not spread to Minnesota or any other states.
Elizabethkingia anophelis is named after American bacteriologist Elizabeth O. King who first reported it in 1959.