A study by the university of Aberdeen has revealed that slugs could be a factor in the spread of E. coli in salad vegetables.

Researchers believe that the slug could be a vehicle for spreading the deadly bacterial strain.

E. coli O157 is a killer, proving fatal in three to five per of infected humans. It is a major cause of bloody diarrhoea and acute renal failure, as well as a major cause for concern for the food industry.

According to the Aberdeen scientists, the slug’s tendency to contaminate leafy vegetables often targeted for human consumption identifies them as likely source for E. coli transmission.

Lab tests showed that E. coli O157 exists in 0.21 per cent of field slugs on a sheep farm in the UK. The slug species, Deroceras reticulatum, can maintain viable E. coli on its external surface for 14 days, it was also discovered.

Slugs that were fed E. coli shed viable bacteria in their faeces persisting for up to 3 weeks. "This study provides evidence that slugs can act as vectors of E. coli O157 from an environmental source to fruit or vegetables," said researchers. "The research demonstrates that E. coli in D. reticulatum has a relatively long external and internal survival time.”

Salad ingredients handlers should have put procedures for testing of processing plants and products for dangerous bacteria such as listeria and E. coli in place by January 1. The procedures, as set out by the Microbiological Criteria for Foodstuffs regulation, seek to harmonise the industry's procedures for detecting the presence of dangerous bacteria.

The findings were published in the January 2006 issue of Applied and Environmental Microbiology.

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