The 15 cases of E. coli O111 reported in Minnesota this summer were probably linked to green whole head cabbage, says the state’s health department. Health officials’ routine monitoring identified the cases of illness associated with Shiga toxin-producing E. coli O111. Bacterial isolates from all of the cases had the same DNA fingerprint. The illnesses occurred between June 25 and July 3. Four of the people who became ill were hospitalized, and all have recovered. No new cases connected with this outbreak have been identified in Minnesota since July 10, but there have been single cases of illness matching the outbreak strain in three other states. Minnesota investigators interviewed 14 of the cases: 13 of them ate at 9 different Applebee’s restaurants in Minnesota, and one ate at Yard House. Many of those who became ill had reported eating the Oriental Chicken Salad at Applebee’s, leading Applebee’s to voluntarily pull the menu item and specific ingredients from their menu for a time. It was returned to the menu after Applebee’s obtained different sources for the ingredients. All the victims ate green whole head cabbage, which Minnesota officials traced to a common supplier outside the state and believe was contaminated before it reached the restaurants. The Minnesota Department of Health and the U.S. Food and Drug Administration are continuing to investigate the source. Symptoms of illness caused by E. coli O111 typically include stomach cramps and diarrhea, often with bloody stools, but only a low-grade or no fever. People usually become ill two to five days after exposure, but this time period can range from one to at least eight days. Most people recover in five to 10 days. Complications from infection are more common among those with weaker immune systems, including young children and the elderly. As with E. coli O157:H7, infection with E. coli O111 should not be treated with antibiotics, as this practice might promote further complications. The genetic strain of E. coli O111 from this outbreak had not previously been seen in the U.S.