In early July 2004, The Pennsylvania Department of Health (PDOH) became aware of an increase in reported Salmonella infections in the state. By July 9, the PDOH Public Health Lab (PHL) had identified at least 12 Salmonella javiana cases among residents of a widespread geographic area, and PDOH notified the Centers for Disease Control and Prevention (CDC) that an apparent foodborne Salmonella outbreak was occurring. Active case finding was expanded to include nearby states. Ohio, Maryland, and West Virginia all reported an increase in Salmonella javiana cases.
Case-patient interviews implicated food prepared and purchased at Sheetz convenience stores in Pennsylvania and Ohio as the source of the Salmonella outbreak. Cases indicated that a variety of Sheetz menu items had been consumed in the 72 hours before symptom onset. In particular, many of the ill individuals said they had eaten lettuce and/or tomatoes as part of sandwiches, wraps, and salads prepared at Sheetz deli counters.
On July 12 Sheetz officials authorized the removal of all produce with an expiration date of July 12, 2004 from stores. The company alerted Coronet Foods, a Wheeling, West Virginia-based company, that Coronet-supplied produce might be contaminated with Salmonella. The U.S. Food and Drug Administration (FDA) began working with Sheetz and Coronet Foods on a product trace-back.
On July 14, 2004, PDOH announced that a Salmonella outbreak associated with food prepared at Sheetz convenience stores was being investigated. The CDC and the PDOH began a coordinated multi-state case-control outbreak investigation. Pennsylvania, West Virginia, Maryland and Ohio had reported a combined total of 56 cases of salmonellosis in persons who had eaten food purchased from a Sheetz store.
For the case-control study, cases were defined as persons culture-confirmed with Salmonella who ate at a Sheetz convenience store in late June or early July. Controls were Sheetz customers who had not become ill with vomiting or diarrhea within seven days of eating Sheetz-prepared food.
On July 16, 2004 PDOH issued a Health Advisory stating that 70 reported Salmonella cases had been associated with eating at Sheetz deli counters throughout the state. The same day, Coronet Foods publicly acknowledged that it had supplied sliced Roma tomatoes to Sheetz stores. The FDA collected multiple food samples from the Coronet facility for laboratory-testing.
By July 19, 2004 over 100 cases of Salmonella linked to consumption of food purchased at Sheetz had been reported in residents of Pennsylvania, Maryland, Ohio, West Virginia, and Virginia. Preliminary results of data collected in the case-control study showed a statistical association with illness and consumption of tomatoes.
On July 13, the Pennsylvania Department of Agriculture (PDOA) announced that Salmonella had been found in an unopened bag of sliced Roma tomatoes obtained from a Sheetz store in Greencastle, Pennsylvania. The tomatoes had been distributed to the Sheetz store by Coronet Foods. Further analysis revealed that the tomatoes were contaminated with Salmonella anatum, and investigators expanded their investigation to include cases of Salmonella anatum.
Pulsed field gel electrophoresis (PFGE) analysis of Salmonella javiana isolates was conducted at state public health laboratories and at CDC labs. An indistinguishable pattern was found in isolates obtained from persons who had consumed tomatoes included as an ingredient in food prepared at Sheetz as well as in isolates obtained from persons who had consumed tomatoes at places other than Sheetz. In fact, Pennsylvania and Maryland reported more than 40 cases of individuals who were ill with the outbreak strain but did not eat tomatoes in food prepared at a Sheetz convenience store.
By July 23, 2004, 289 cases of Salmonella had been reported in Pennsylvania, Ohio, Maryland, Virginia, and West Virginia. Both the PDOH and the FDA, working with the CDC, publicly identified Roma tomatoes as the likely source of the outbreak. PDOH continued issuing related Health Updates throughout the course of its investigation, and by August 6, 2004 had identified over 330 cases of Salmonella javiana in Pennsylvania, and over 80 cases in neighboring states.
Preliminary data suggested that as many as 564 confirmed cases of salmonellosis associated with consumption of contaminated tomatoes were reported in five states: Pennsylvania, Maryland, Ohio, West Virginia, and Virginia. Seventy percent were associated with tomatoes in food prepared at Sheetz convenience stores. Five separate serotypes of Salmonella were eventually associated with the outbreak. Most of the cases were infected with Salmonella javiana; other outbreak associated strains were Salmonella typhimurium, Salmonella anatum, Salmonella Thompson, and Salmonella Muenchen.
FDA investigators traced the contaminated tomatoes back to farms in Florida and possibly South Carolina, but the investigators were also told that farms from five different states may have supplied tomatoes to Coronet Foods at relevant times.
Marler Clark represented 137 people in Salmonella litigation against Sheetz, Coronet Foods and various others that supplied tainted tomatoes to Sheetz stores. All claims were resolved in the summer of 2006.