In October of 2003, the San Mateo County Health Services Agency (SMCHSA) was notified that residents of The Sequoias, an upscale retirement center, had become ill with E. coli O157:H7. SMCHSA investigated the outbreak, conducting both environmental and epidemiologic investigations.
During its investigation, SMCHSA learned that Sequoias employees are not involved in food service or kitchen management. At the time of the outbreak, the Sequoias contracted with Sodexho, an outside vendor, to perform all food service functions. Stool samples were collected from all Sequoias and Sodexho staff, as well as from Sequoias residents who reported at least one episode of diarrhea since September 21. The samples were tested, and those with positive E. coli O157 isolates were sent to the California Department of Health Services (CDHS) Microbial Diseases Laboratory for confirmation and serotyping.
A case-control study was conducted, with a case being defined as, “any resident or employee experiencing two or more episodes of diarrhea in a 24-hour period between 9/21/2003 and 11/3/2003.” During the case-control analysis, the case definition was narrowed to include only laboratory-confirmed cases and probable cases, which were those without laboratory confirmation but that involved bloody diarrhea or hemolytic uremic syndrome. Controls were selected from the frequent dining partners of cases and, alternatively, at random from the resident roster.
During the environmental investigation, an inspector noted that the Sequoias kitchen met industry standards and was free from violations. Two days later, however, a follow-up investigation noted that several refrigeration units were above 41 degrees Fahrenheit, and a build-up existed on the ice machine. Corrections of these violations were completed by the next inspection.
By the end of the investigation, sixteen confirmed and probable E. coli cases had been identified. Of these, thirteen were culture-confirmed. All had onset between October 9 and 17, and all cases were residents of “independent living” and “skilled nursing.” The CDHS subtyped all thirteen available isolates using pulsed-field gel electrophoresis (PFGE), and twelve had indistinguishable PFGE patterns.
Analysis done of the sixteen “case” food histories identified only one food item that was associated with illness: raw spinach. The SMCHSA Final Report concluded, “[n]o other common exposures were found. No food handlers were identified with diarrheal illness during the exposure period and no employees cultured positive for enteric pathogens.”
On May 3, 2004, the California Department of Health Services Emergency Response Unit completed its outbreak investigation report, concluding that spinach served at The Sequoias was the source of the E. coli outbreak.
Marler Clark represented one elderly woman who survived her E. coli infection, and the family of another woman who died after eating the E. coli-contaminated spinach served at The Sequoias. Their claims were resolved in September of 2006.