ADLib Glossary (E)

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E. Coli

Escherichia coli

is a micro-organism found in the alimentary tract of most animals. There are four recognised classes of enterovirulent E.coli that cause gastro-enteritis in humans. One of these strains (E.coli 0157) is enterohemorrhagic and causes haemolytic uraemic syndrome (HUS) or haemorrhage colitis. This is an acute disease of humans which is characterised by sever cramping (abdominal pain) and diarrhoea which is initially watery but becomes bloody. Occasionally vomiting occurs. Fever is either low or absent. The illness lasts, on average, eight days, but can be fatal. In one study 59% of patients required hospitalisation, 15% developed HUS and 5% died.

A bovine source of infection has been associated with the majority of recorded outbreaks of E.coli infection in humans. The first recorded outbreak was in the U.S.A. in 1983 and was linked to ground beef consumption. Studies of the organism have been made in this country since the late eighties.

Human infections arise from the ingestion of a very small number of E.coli 0157 organisms. In every case these organisms will be present due to faecal contamination. This contamination may be due to person to person transmission, contact with animals, eating contaminated food or contact with a contaminated environment.

The number of recorded cases of E.coli infection varies across the UK, in England and Wales 1 to 2 cases are recorded per 100,000 population each year, whilst in Scotland there are approximately 5 cases per 100,000 population each year.

Recent outbreaks have increased public awareness and concern over this organism finding it's way into the food chain. In 1996 an outbreak in Scotland saw 496 people affected and twenty adults die.

Good hygiene practices and careful food handling are essential to reduce the risk of contamination. The prevalence of the organism in the environment and in the gut of all animals means that elimination at source is impossible. This means that the food industry is finding it necessary to increase care at abattoirs and in food handling generally to reduce contamination.

On farm there are several ways in which infection levels can be kept low. As heat and UV light can help kill E. coli bacteria, stacking manure so that the pile heats up and storing slurry in a pit for six weeks will all help kill the bugs. Straw bedded yards also heat up, killing bacteria but fresh straw should be kept on top keeping dung off of livestock. Slurry-based housing must be kept clean and livestock should be kept off of pasture where fresh manure or slurry has been spread for around six weeks.

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