On April 26, 2010, Douglas County Health Department (DCHD) received five Salmonella positive test results from a local laboratory. This influx of positive Salmonella reports immediately caught the attention of DCHD communicable disease staff as five cases in a single day is well above the county’s typical annual number of reported Salmonella cases. There were 17 reported cases in 2008 and 9 reported in 2009. County officials interviewed case-patients and a common exposure quickly emerged—Los Dos Amigos restaurant in downtown Roseburg.
On April 27, an inspection of the restaurant by Douglas County Environmental Health (DCEH) found two critical violations: 1) Raw or ready-to-eat food was not properly protected from cross contamination, and 2) food employees did not wash their hands as often as necessary. Inadequate changing of gloves and lack of sanitizer in the wipe cloth bucket were also noted.
Environmental samples were collected on April 27, 28, and May 5. While the results did not return positive for the presence of Salmonella, this was not surprising considering—and as the DCHD also notes—“the samples were taken after the peak period of concern for exposure (04/09—04/17).”
State and local public health investigators identified a total of 38 culture-confirmed cases of Salmonella serotype Enteritidis. An additional 35 case-patients who were not laboratory confirmed but were epidemiologically linked to Los Dos Amigos restaurant were classified as “presumptive” cases. Ninety seven percent (97%) of the culture-confirmed cases shared an indistinguishable two-enzyme genetic match by PFGE analysis, further supporting the hypothesis there was a common source of infection. After conducting food history interviews, a number of uncooked food items were found to be statistically associated with illness, including guacamole, cilantro, and green onions, but no one food item could be singled out at the likely vehicle for the outbreak.
Of the genetically indistinguishable culture-confirmed cases, two were employees of the restaurant. Both were interviewed. One denied having any gastrointestinal symptoms while the other, who had an illness onset of April 16, admitted to working while ill with diarrhea on April 16, 17, 18, 19, 21, and 22. As noted by the DCHD, “any food handler ill with diarrhea are required to be excluded from work until they are no longer symptomatic.” They also could not rule out whether the food handlers also became ill from eating at the restaurant.