In July 2015, an increase in Salmonella reports was reported from one local health department. Comparisons to historical data did not indicate increases over baselines and initial interviews did not reveal epidemiologic linkages. A geographically focused PFGE-matched cluster (Xbal pattern JGGX01.0094) associated with Salmonella javiana was identified. CDC was notified and a national cluster code (1508NJJGG-1) was issued with the majority of cases coming from NJ. The following describes the NJ investigation associated with this multi-state cluster.
METHODS:
A standardized Salmonella worksheet was initially used to detect common exposures among cases. NJDOH developed a focused questionnaire based on initial information collected to interview or re-interview all PFGE matching cases. Questions related to a Mexican-style chain restaurant were incorporated as initial interviews suggested a common link to this restaurant. Analyses were shared with food safety partners who conducted investigations and assisted with food trace-backs.
RESULTS:
Thirty-three PFGE-matched NJ cases were identified with an onset range of July 9 to August 14, 2015 and median age of 24 years. Seventy-five percent of cases occurred in two NJ counties. Sixty-two percent of case-patients consumed a meal at a Mexican-style chain restaurant within seven days prior to onset. Four chain locations were identified with 80% of case-patients consuming a meal at one location. A burrito bowl, chicken, fresh salsa, cheese and lettuce were consumed by the majority of cases. Ingredient specific analysis also revealed increased consumption of cilantro and oregano. No ill food workers and no poor food handling practices were observed at the Mexican-style chain restaurant locations inspected. Nationally, 86 isolates matching PFGE pattern were identified, and nine cases were tested using whole genome sequencing (WGS). The final national case count was 37 (NJ=33; non-NJ=4). Seven of the nine WGS-matching cases ate at five different locations of this Mexican-style chain restaurant nationwide.
CONCLUSIONS:
This was a multi-state cluster of S. javiana with a large number of case-patients reporting consumption at a common restaurant. Various restaurant locations were identified, suggesting a common contaminated product disseminated to multiple restaurants. This cluster was likely associated with a ready-to-eat produce (i.e., lettuce, tomato, herbs) product. Larger numbers of case-patients at certain locations are suggestive of a breach in safe food handling practices associated with produce items. While trace-backs were conducted, a common source or vehicle linking cases in this cluster was not found.