The Web-based case-control study was distributed on July 31 to the 369 persons who responded to the first survey. By August 2, a total of 222 persons (60%) responded. Of 217 valid responses, 41(19%) were ill persons who met the case definition; the remaining 176 were healthy controls. Ill persons were significantly more likely to report eating dishes containing diced Roma tomatoes than were well persons (44% of ill vs. 15% of well, OR = 4.3, 95% CI 2.1-9.1). Other food items that were significantly associated with illness on univariate analysis were dishes containing shredded iceberg lettuce (OR = 3.7, 95% CI 1. 8-7.4) , pre-shredded cheddar cheese (OR = 2.9, 95% CI 1.5-5.9), fresh ground beef (OR = 3.0, 95% CI 1.4-6.4), and pre-sliced beefsteak tomatoes (OR = 4.6, 95% CI 1.1-19.4) ( Table) . In multivariable logistic regression modeling, only diced Roma tomatoes remained independently associated with illness at the 0.05 significance level.