Ninety seven customers of 49 Subway Restaurant locations, in 28 Illinois counties, developed Salmonella Hvittingfoss, a rare strain of Salmonella. The counties where cases had eaten included Bureau, Cass, Champaign, Christian, Coles, Dekalb, DeWitt, Ford, Fulton, Henry, Knox, LaSalle, Livingston, Macon, Marshall, McLean, Moultrie, Ogle, Peoria, Rock Island, Sangamon, Schuyler, Shelby, Tazewell, Vermilion, Warren, Will and Winnebago counties. On June 2, the restaurant chain began removal of lettuce, tomatoes, green peppers and onions from the inventory based on an early review of what food items had been most frequently consumed by case-patients; these were then replaced with a different supply. Twelve of the food handlers at seven of the Subway outlets were infected with the same strain of Salmonella Hvittingfoss. The outbreak report submitted to the Centers for Disease Control described that eating lettuce, tomatoes, or olives were statistically significant, risk factors for illness. The patterning of the illnesses suggested that one of Subway Restaurants suppliers, Sysco Central Illinois, Inc., was the likely source of the implicated produce. Food samples were tested, however none of these samples yielded Salmonella Hvittingfoss.