On Wednesday, November 22, 2017, Tri-County Health Department (TCHD) identified four laboratory-confirmed cases of Salmonellainfection with a common food exposure through routine case investigation. All four of the confirmed cases reported eating food from La California Restaurant, located at 1685 Peoria Street in Aurora, Colorado. TCHD investigated to implement disease control measures and identify the source of illness. Its investigation led TCHD to conclude that this outbreak of Salmonella I,4,5,12:i- (CDPHE PFGE patterns 07-T and 13-D) was associated with consuming food prepared at La California Restaurant. Based on results from the food exposure analyses and the environmental assessment, consumption of the family combo meal was the most likely menu item associated with Salmonella infection.
Fifteen (45%) of the cases were female. The case median age was 25 years (1-71 years). The range of illness onset was November 4, 2017 to November 26, 2017. The incubation period of the cases ranged from 8 hours to 5 days (median 16 hours). The median duration of illness was 7 days (range 6 hours to 16 days). Three confirmed cases were hospitalized, and one confirmed case died.
Each laboratory-confirmed case of Salmonellainfection was interviewed with a Colorado Department of Public Health and Environment (CDPHE) Salmonella Case Investigation Form to assess symptoms and exposures. TCHD Communicable Disease Epidemiologists conducted supplemental hypothesis-generating interviews with the initial four cases reported through routine surveillance to TCHD. A standard TCHD food worker and manager questionnaire was used to conduct interviews with restaurant employees. To explore possible associations between food exposures and illness, TCHD conducted a case-control study among patrons who consumed food from La California during November 1 to November 30, 2017. Additional case ascertainment resulted from interviewing dining companions of cases, restaurant employees, and persons enrolled in the case control study.
Although none of the five restaurant employees reported experiencing gastrointestinal symptoms during the month of November 2017, all five submitted stool specimens on November 22, 2017 for Salmonellatesting at CDPHE laboratory. One restaurant employee had a positive culture for the outbreak strain, Salmonella I,4,5,12:i-, and was excluded from work from November 27, 2017 until two consecutive culture results were negative. This employee denied having gastrointestinal symptoms and worked at the restaurant before being excluded by TCHD.