Risk of infection with Salmonella and Listeria monocytogenes due to consumption of ready-to-eat leafy vegetables in Brazil

The current study was carried out to estimate the risks of infection due to consumption of RTE vegetables contaminated with Salmonella and Listeria monocytogenes in Brazil. The risk assessment model was composed of five different modules comprising the retail-consumption steps. Scenarios were simulated using prevalence and concentration levels reported in RTE vegetables in Brazil as well as considering values 10 times lower. In addition, scenarios in which temperature during transportation and storage are maintained below 5 °C were also evaluated. Models built in Excel spreadsheets were run (100,000 iterations) using @Risk software. The two outputs were risk of infection per month (probability of infection per month due to consumption of RTE vegetables) and number of infections per month (number of people that consumed RTE vegetables and get infected per month). The QMRA models predicted that the mean risk of Salmonella infection per month is 5.7E-03, while the mean risk of infection for L. monocytogenes was 8.1E-06 per month. The reduction of prevalence of Salmonella from 1.7% to 0.17% resulted in a decrease of risk of infection per month by about 6 times. In the case of L. monocytogenes, the reduction of prevalence from 2.2% to 0.22% resulted in decrease of risk of infection from 8.1E-06 to 1.0E-06. The risks and number of cases predicted in scenarios in which temperature was kept below 5 °C were reduced for both pathogens studied when compared to scenarios where this was not the case. The scenario where prevalence and concentration of pathogens was reduced and where temperature was <5 °C led to the lowest number of infections due by Salmonella and L. monocytogenes (187 and 3.3E-05 cases, respectively). The results suggest that effective mitigation strategies need to be adopted. The strict control of temperature during transportation, storage and consumption was more effective to reduce risk and number of cases due to L. monocytogenes than to Salmonella. More data is needed to improve the accuracy of risk assessment models developed.