WISCONSIN, UNITED STATES - A rare bloodstream infection is mystifying Wisconsin officials as they try to determine whether it's behind the deaths of 18 people in the state. The illness has already affected 48 people since late last year. According to the Wisconsin Department of Health Services (DHS), the cases have been logged since November 1, 2015, though the Division of Public Health was first notified about six possible cases between December 29 of last year and January 4, 2016. Since then, the number of cases has continued to rise, mostly affecting people over 65 years old. The illness in question is called Elizabethkingia, a bacteria that infects the bloodstream and usually affects people with weakened immune systems and underlying health issues such as cancer or diabetes. So far, 18 people who tested positive for the disease have died, but officials haven't been able to confirm if Elizabethkingia was responsible. Now, Wisconsin officials have called in the US Centers for Disease