Human noroviruses (HuNoV) are the leading cause of outbreaks of nonbacterial gastroenteritis in the U.S., and are often implicated in... Show moreHuman noroviruses (HuNoV) are the leading cause of outbreaks of nonbacterial gastroenteritis in the U.S., and are often implicated in outbreaks associated with ready-to-eat foods, such as salads. Such foods may be extensively handled, and norovirus may be transferred readily between infected food handlers and food surfaces. The aim of this study was to investigate norovirus transfer between surfaces and romaine lettuce which were commonly used in the preparation of fresh food. Fresh Romaine lettuce was cut into 25cm2 pieces and inoculated with 25 μl (approx. 7-log PFU) murine norovirus (MNV-1) per leaf. After 10 min air-drying, 5 g piles of inoculated leaves were cut with a sterile stainless steel knife on a sterile cutting board. Sampling sponges soaked in Dulbecco’s Modified Eagle’s Media (DMEM) were used to swab blade and board surfaces for MNV-1 transferred from lettuce. In some cases, fresh, uninoculated Romaine lettuce was chopped using the contaminated knife and board. MNV-1 transferred to the chopped lettuce was recovered by stomaching in DMEM and enumerated by plaque assay. MNV-1 transfer was lower from contaminated lettuce to cutting board (p<0.05) than that from a contaminated cutting board to lettuce. This same trend was observed between a stainless steel knife and lettuce. The MNV-1 transfer coefficient was lower when contaminated lettuce was chopped on a wood board (p<0.05) compared to a polyvinyl cutting board. Norovirus transfers readily between surfaces common in the preparation of fresh produce preparation, but the transfer coefficient appears to be dependent on the surface type. This research provides the scientific basis for the development of a risk assessment model for norovirus transfer during the fresh food preparation. M.S. in Food Safety and Technology, December 2012 Show less
