Modelling the contamination of lettuce with Escherichia coli O157:H7 from manure-amended soil and the effect of intervention strategies.
OBJECTIVE
A growing number of foodborne illnesses has been associated with the consumption of fresh produce. In this study, the probability of lettuce contamination with Escherichia coli O157:H7 from manure-amended soil and the effect of intervention strategies was determined.


RESULTS
Pathogen prevalence and densities were modelled probabilistically through the primary production chain of lettuce (manure, manure-amended soil and lettuce). The model estimated an average of 0.34 contaminated heads per hectare. A minimum manure storage time of 30 days and a minimum fertilization-to-planting interval of 60 days was most successful in reducing the risk. Some specific organic farming practices concerning manure and soil management were found to be risk reducing.


CONCLUSIONS
Certain specific organic farming practices reduced the likelihood of contamination. This cannot be generalized to organic production as a whole. However, the conclusion is relevant for areas like the Netherlands where there is high use of manure in both organic and conventional vegetable production.


CONCLUSIONS
Recent vegetable-associated disease outbreaks stress the importance of a safe vegetable production chain. The present study contributed to this by providing a first estimate of the likelihood of lettuce contamination with E. coli O157:H7 and the effectiveness of risk mitigation strategies.
Franz
E
E
Biological Farming Systems Group, Wageningen University and Research Centre, Wageningen, the Netherlands. eelco.franz@wur.nl
Semenov
A V
AV
van Bruggen
A H C
AH
D000383:Agriculture / Q000379:methods*; D015169:Colony Count, Microbial; D004927:Escherichia coli Infections / Q000453:epidemiology*; D019453:Escherichia coli O157; D018545:Lactuca / Q000382:microbiology*; D008372:Manure / Q000382:microbiology*; D008962:Models, Theoretical; D009426:Netherlands / Q000453:epidemiology; D015995:Prevalence; D012988:Soil Microbiology; D013997:Time Factors
D008372:Manure