Health officials in four states are working with the Centers for Disease Control and Prevention and the U.S. Food and Drug Administration to investigate a four state Listeria outbreak tied to a Wisconsin cheesemaker, the Minnesota Department of Health announced on Wednesday. One patient has died. Minnesota health officials said the outbreak has been linked to Les Frères cheese made by Crave Brothers Farmstead Classics Cheese, a Wisconsin producer. At least three other states are involved but have not yet been named. Mary Choi, a spokeswoman for the Minnesota Department of Health, said she could not name the other states, but noted that CDC is working on an outbreak announcement. “Two people in Minnesota so far have become ill. Both were older adults. They became ill in early June. Both were hospitalized and one died,” according to the announcement from Minnesota. “The Department of Agriculture is testing samples of the cheese and early results indicate presence of Listeria; confirmation is pending.” Health officials are warning consumers who may have purchased Les Frères, Petit Frère and Petit Frère with Truffles to not eat the products “until more information becomes available from the investigation.” The Minnesota Department of Agriculture has advised grocery stores and distributors to pull and not sell the products until further information is available, health officials said. Listeriosis is a serious infection caused by eating food contaminated with the bacterium Listeria monocytogenes. The disease affects primarily older adults, pregnant women, newborns, and persons with weakened immune systems. Approximately 4 to 10 cases of listeriosis are reported in Minnesota each year. Symptoms of listeriosis include fever, muscle aches, headache, stiff neck, confusion, loss of balance, and convulsions. Infected pregnant women may experience only a mild, flu-like illness; however, infections during pregnancy can lead to miscarriage or stillbirth, premature delivery, or infection of the newborn. Symptoms often begin 3 weeks after infection, but it could take anywhere from 3 to 70 days. Anyone who believes they may have become ill with listeriosis should contact their health care provider.