On July 8, 2016, the Oregon State Public Health Laboratory (OSPHL) identified seven cases of Salmonella Newport infection that matched by Pulse Field Gel Electrophoresis (PFGE), with onsets from 6/9/16-6/29/16. Cases were from three counties in Oregon (Multnomah, Washington, and Marion counties) and Clark County in Washington State. In collaboration with local public health officials, Oregon Health Authority (OHA) epidemiologists investigated to determine whether the cases stemmed from a common source.
An outbreak case was defined as a person with Salmonella Newport infection with PFGE pattern matching the outbreak strain (SNEX-179). The PFGE pattern from the cases was posted on the national PulseNet laboratory network to identify any matching cases in other states.
Five of the 7 original cases reported having eaten at the Hollywood Baja Fresh location in Portland, though on different dates. Multnomah County Environmental Health Specialists inspected this particular restaurant. To try ascertain the time period of at-risk exposures and to find controls for comparison with case food exposures, OHA epidemiologists contacted the corporate office of the restaurant, and requested a list of persons who ordered on line in June. A survey monkey questionnaire was prepared to send to customers who ordered online. One of the cases ate there and also ordered take-out from the restaurant for co-workers. Names and contact numbers of co-workers of the case were obtained to find more cases and controls.
On July 13, 2016, OHA epidemiologists took 16 environmental samples from the restaurant and sent them to IEH laboratory in Seattle, WA. Samples were taken from salad spinner, knives, blender, vegetable slicer, chopper, dicer, salsa bar, walk-in cooler, ice machine drain, and the floor drain.
A total of 13 cases were reported with onsets during June 5-July 12, 12 were from Oregon, and 1 from Washington State. There were 7 females and 6 males. The age range was 27-82 years. Cases were from Multnomah (9), Washington (2), Marion (1), and Clark County, WA (1). Of the 13 cases, 9 ate at Baja Fresh (same location) during June 1-June 25. Two cases denied eating at Baja Fresh, 1 case refused to be interviewed, and 1 case was lost to follow-up. One case was the household member of another case, had illness onset 6 days afterwards, and was deemed a secondary case.
The only controls available who had eaten food from Baja Fresh were 7 co-workers of one of the cases; they were unable to recall what they had eaten. The corporate office did not provide a list of persons who ordered on line in June, and a comparative epidemiologic study could not be conducted for lack of informative controls.
Exposure to some food or drink from the Hollywood Baja Fresh in Portland caused this outbreak. A specific vehicle could not be implicated epidemiologically due to lack of controls. The fact that nearly all interviewed cases from several counties recalled having eaten food purchased at this single Baja Fresh facility suggests strongly that the contamination occurred there, perhaps from a food handler or from the environment, rather than upstream in the food supply. No new cases had onset after July 12, 2016, and the last case's Baja Fresh exposure was June 25th - i.e., before the outbreak was recognized.