In July 2011, CDC and state and local health agencies investigated an outbreak of Salmonella Typhimurium infections. Consuming seedless watermelon was associated with illness. Twenty-three states reported 143 cases with the outbreak strain designated by PFGE pattern JPXX01.0324.

Minnesota Department of Health (MDH) interviewed Minnesota individuals with the outbreak strain in Minnesota. Eight (89%) of nine cases reported consuming watermelon during the week prior to their illness onset. Seven of the 9 reported consuming seedless watermelon. Using the 2007 FoodNet Population Survey for comparison, MDN investigators conducted binomial probability analysis. Based on the observed 89% exposure among Minnesota and estimated maximum 56% background rate of exposure in the general population, a significant association between consumption of watermelon and illness (p=0.04) was identified.

Minnesota Department of Agriculture (MDA) conducted a traceback of seedless watermelon purchased at two grocery chain stores. Both chains reported purchasing seedless watermelon from distributors in Vincennes, Indiana. However, records from the two distributors did not indicate a common supplier between the two.