Escherichia coli: On-farm contamination of animals, OIE Review
Fairbrother JM and Nadeau E (2006). Escherichia coli: On-farm contamination of animals. Revue scientifique et technique de l’Office International des Epizooties 25(2): 555-569.
PDF file of the OIE E. coli review
Summary
Escherichia coli is one of the main inhabitants of the intestinal tract of
most mammalian species, including humans and birds. Shiga toxinproducing E. coli (STEC), also called verotoxinogenic E. coli, usually
do not cause disease in animals but may cause watery diarrhoea,
haemorrhagic colitis, and/or haemolytic uraemic syndrome in humans.
Zoonotic STEC include the O157:H7 strains and, with increasing
frequency, certain non-O157 strains. The importance of non-O157
zoonotic strains is probably underestimated as they have been less
well characterised and are more difficult to detect in samples than
O157:H7. Another large subset of STEC strains has been isolated
from animals but has not, at the present time, been associated with
disease in animals or humans. Cattle and other ruminants are the most
important reservoir of zoonotic STEC, which are transmitted to
humans through the ingestion of foods or water contaminated with
animal faeces, or through direct contact with the infected animals or
their environment. The main sources of STEC infection of cattle onfarm
are the drinking water, the feed, and the immediate environment
of the animal. Risk factors that have been identified for infection of
animals with O157 STEC include age, weaning, movement of the
animals, season, feed composition, and the ability of the bacteria to
persist in the environment. On-farm control of the zoonotic risk of
human infection with STEC should primarily target the main source of
contamination: the animal reservoir. Various strategies to reduce
intestinal colonisation of cattle by zoonotic STEC have been tried with
varying results, including vaccination, treatment with probiotics, such
as direct-fed microbials or competitive exclusion, administration of
bacteriophages, and modification of the diet.
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