The two public health agencies conducted a case-control study, tracing the source of illness to ready-to-eat foods prepared at Robinswood, likely a garnish. During their investigation, the investigators found multiple food-handling violations that supported a conclusion that the ready-to-eat foods had been cross-contaminated through contact with raw meat products.
In conjunction with patient interviews, the case-control study, and kitchen inspection, WDOH conducted genetic testing on the E. coli O157:H7 isolates from each of the laboratory-confirmed cases. Each of the four identified to be part of the Robinswood outbreak was infected with a genetically indistinguishable strain of E. coli O157:H7.
In July of 2006, Marler Clark resolved the claim of the family of a Robinswood resident who became ill with E. coli O157:H7 and hemolytic uremic syndrome during the outbreak, and died.