In addition to the general Salmonella outbreak investigation, a number of epidemiologic investigations were conducted by public health officials in 11 states. These various investigations revealed that beginning in April, 2010 there were 29 restaurants or event clusters where more than one ill person with the outbreak strain had eaten. The CDC reported:
Data from these investigations suggest that shell eggs were a likely source of infections in many of these restaurants or event clusters. Wright County Egg, in Galt, Iowa, was an egg supplier in 15 of these 29 restaurants or event clusters.
Further investigation into the source of the Salmonella outbreak led CDC and Food and Drug Administration (FDA) investigators to the Wright County Egg production facilities. FDA investigators found Salmonella in numerous environmental samples collected at the Wright County Egg facility. In addition, the finding of deplorable conditions at Wright County Egg led to a national outcry for better oversight of egg production facilities.
A Congressional investigation uncovered further evidence of poor conditions at the Wright County Egg facility and risk of illness to consumers. Records presented at Congressional hearings included environmental sample reports from the egg producer’s facility in and around Galt Iowa from between 2008 and 2010 that indicated that Wright County Egg received 426 positive results for Salmonella, including 73 samples that were potentially positive for Salmonella Enteritidis. The testing included 66 positive samples for Salmonella on May 27, 2010 alone.
Investigations by the CDC and state and local public health agencies ultimately led to the conclusion in December 2010 that nearly 2,000 reported Salmonella cases were likely associated with the egg outbreak.