Purpose: The presented study simulated NoV transmission during the preparation of deli sandwiches in a sandwich bar.
Methods: A simulation model was built by combining the GoldSim and @Risk software packages. The working situation involved three food handlers working during a 3 hour shift on a common working surface. The model consisted of three modules. A first module simulated preparation of the deli sandwiches and contained the NoV reservoirs, locations within the model allowing the accumulation of NoV and the working of intervention measures. NoV reservoirs included (1) hands of all food handlers, (2) prepared sandwiches and (3) food contact surfaces. A second module covered the contamination sources being (1) initial contamination of the lettuce used on the sandwiches and (2) contamination of the sandwich if one of the food handlers was a NoV shedder. A third module included four intervention measures: hand/surface disinfection during preparation of the sandwiches, wearing/changing of gloves and hand washing after a restroom visit.
Results: A NoV shedding food handler could – in the absence of NoV transmission intervention measures – cause mean levels of 31 ± 11, 61 ± 17 and 5 ± 1 NoV particles present on the foods, hands and working surfaces, respectively. In this scenario, 90.2% of all deli sandwiches contained >18 NoV particles, the assumed NoV infectious dose. The inclusion of hand/surface disinfection and hand gloving as single intervention measures resulted only in marginal reductions of NoV levels in the reservoirs while a high compliance of hand washing after a restroom visit did reduce NoV presence on all reservoirs.
Significance: The inclusion of hand/surface disinfection and glove wearing/changing as single intervention measures was not effective in the model, as only marginal reductions of NoV levels were noticeable in NoV reservoirs. On the other hand, a high compliance of hand washing after a restroom visit severely reduced NoV presence on all NoV reservoirs. The presented model showed that good handling practices in deli sandwich bars is an efficient way to prevent NoV transmission.