On February 24, 2009, the Nebraska Department of Health and Human Services identified bacterial isolates from fourteen Nebraska residents who were infected with Salmonella Saintpaul. Salmonella Saintpaul is an uncommon serovar; only three Saintpaul isolates were identified in Nebraska in 2008. By PFGE testing, the genetic fingerprints of six of the fourteen cases matched exactly, and results were pending on the remaining eight cases. Onsets of illness for these initial fourteen cases stretched from the beginning to the middle of February 2009.

Approximately two days later, Nebraska health authorities issued a nationwide notice to other state and federal health organizations, inquiring whether there were any additional reports of illness due to infection by Salmonella Saintpaul. Iowa Department of Public Health immediately disclosed that it had received seven recent reports of Salmonella Saintpaul infection in Iowa residents. Nebraska and Iowa health authorities immediately began an investigation into the sudden rash of Salmonella Saintpaul illnesses.

Interviews with confirmed and suspect cases in the developing outbreak soon revealed a pattern of exposure to raw alfalfa sprouts, typically on sandwiches from Jimmy John’s restaurants, in the days before onset of illness. Health authorities from both states, in collaboration with officials from the CDC and FDA, quickly identified CW Sprouts, Inc, a grower from Omaha, as the grower and supplier of the implicated sprout products. On March 3, 2009, CW Sprouts voluntarily recalled its alfalfa, onion, and gourmet sprout products sold under the SunSprout Enterprises brand name.

In the two weeks following CW Sprouts’ March 3 recall, four other mid-western states reported Salmonella Saintpaul illnesses among residents. By March 18, the total number of confirmed cases in the outbreak had risen to 121, including 84 from Nebraska, 27 from Iowa, and five each from South Dakota and Kansas. All illnesses were linked to sprout products grown and sold by CW Sprouts.

On April 26, 2009, the FDA issued a news release regarding another cluster of Salmonella Saintpaul illnesses from Michigan, Minnesota, Pennsylvania, South Dakota, Utah, and West Virginia. PFGE testing done on bacterial isolates from these confirmed illnesses showed that they were indistinguishable from the cases involved in the first outbreak cluster. Onsets of illness for cases involved in this second cluster began March 15, shortly after the illnesses linked to the first cluster of approximately 121 cases had ceased appearing. But because the retail food establishments involved in this second cluster of illnesses had received their sprouts from several different sprout growers, none of which was CW Sprouts, investigators began considering the possibility that the seeds from which all implicated sprouts had been grown were contaminated before the sprouts were cultivated.

This turned out to be exactly the case. Traceback investigation ultimately showed that Caudill Seed and Warehouse, Inc., a Louisville, Kentucky seed wholesaler, had supplied all alfalfa sprout seeds from which all sprouts implicated in both the first and second cluster of illnesses were grown. Ultimately, Caudill Seed identified implicated seeds as those bearing six digit lot numbers that began with 032. On May 1, 2009, Caudill Seed issued a market withdrawal of all implicated seeds.

In total, thirteen states reported 228 confirmed illnesses in both outbreak clusters. Though no deaths were reported, approximately four percent of cases were hospitalized.