Salmonella Enterica Serotype Typhimurium Infection Associated With Cantaloupe — Kentucky, 2012

BACKGROUND:  In July 2012, the Kentucky Department for Public Health identified an increase in reported salmonellosis cases >3 times the Kentucky weekly average. These included an outbreak of Salmonella Typhimurium with a pulsed-field gel electrophoresis (PFGE) pattern rarely reported in Kentucky and that PulseNet matched to cases in other states. We investigated to identify the vehicle and source of the Kentucky outbreak and prevent additional cases.

METHODS:  We defined a case as laboratory-confirmed Salmonella Typhimurium matching the outbreak PFGE pattern isolated from a Kentucky resident during July 7–September 30, 2012. Telephone interviews provided patient food histories for 72 hours before illness onset. We visited grocery stores, collected samples of implicated items, and performed a traceback investigation. Environmental samples for laboratory testing were collected from the farm that grew sampled cantaloupes.

RESULTS:  We identified 70 matching cases of Salmonella Typhimurium with illness onsets July 11–August 22. Median patient age was 58 years (range: 3–100 years); 49 (70%) reported hospitalization, and 3 (4%) died. Among 32 patients interviewed, 27 (84%) reported having consumed cantaloupe. Site visits to grocery stores of interest revealed opportunities for cross-contamination through use of common surfaces and utensils for cutting produce. The outbreak strain was isolated from two cantaloupes collected from a grocery store with a single cantaloupe supplier, Farm A, and from cantaloupes sampled from Farm A fields. PulseNet ultimately linked the outbreak to 240 illnesses in 20 states.

CONCLUSIONS:  Epidemiologic and laboratory investigations traced an outbreak of salmonellosis to a cantaloupe vehicle and through the supply chain to Farm A. The proportion of patients hospitalized was higher than expected for Salmonella Typhimurium, even when considering patients’ age.