Free-range chickens at 'no increased infection risk' 16 Apr 2008
According to scientists at Oxford University, the
free-range environment is not a major source for Campylobacter jejuni infection
in chickens, as is widely believed.
Chicken meat contaminated with the bacterium Campylobacter jejuni is a
major cause of food poisoning in humans, responsible for 340,000 cases in the UK
every year. This has led to increased biosecurity measures that attempt to limit
infection of chickens in intensive, housed conditions. It had been thought that
free-range chickens are more at risk because they cannot be protected from
outdoor sources of infection.
"It was widely thought that free-range chickens were likely to pick up
Campylobacter from the free-range environment, particularly wild birds, but none
of the evidence we have gathered supports this as a major infection source,"
said Professor Martin Maiden* of Oxford University's Department of Zoology who
led the research.
"If this was the case then you would expect to see free-range chickens
sharing genetically similar bacteria with local wild bird populations, but our
study suggests that this is not the case. It is good news as it means that not
being able to extend comprehensive biosecurity measures to free-range poultry is
probably not the threat to human health that had been feared," he
continued.
A total of 975 chickens from 64 flocks were sampled over a period of 10
months as part of the research. Wild bird populations in the areas concerned
were also studied.
* This research was conducted by Professor Martin Maiden, Professor
Marian Stamp Dawkins, Dr Frances Colles, Dr Noel McCarthy and Dr Samuel Sheppard
of the Department of Zoology and Dr Kate Dingle and Dr Alison Cody of the
Nuffield Department of Clinical Laboratory Sciences at the University of
Oxford.
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