Cambridge: Poultry is an important source of protein; almost half the meat we eat in the UK is chicken. And the popularity of chicken is rising: it’s convenient, tasty and cheap. On average we eat around 190g per person per week. Poultry, however, harbours a hidden problem. Around two-thirds of raw chicken sold by British retailers is infected with bacteria called Campylobacter.
is ubiquitous in the environment. All chicken flocks, large or small,
factory-farmed or free range, are susceptible to infection. The bacteria
have the ability to survive the production chain from farm to fork.
Adequate cooking, however, kills the bacteria and makes chicken safe
to eat. Consumers are advised not to wash chicken before cooking and to
follow basic hygiene rules when handling raw chicken.
If Campylobacter is ingested by humans, it can lead to
diarrhoea. Four out of five cases of food poisoning in the UK can be
traced to poultry; sickness from Campylobacter costs the
economy an estimated £900 million each year. Recovery can take a week or
more, and infection with the bacteria is also associated with serious
complications – including reactive arthritis and Guillain-Barré
These facts are the driving force behind research being undertaken by
microbiologists Dr Andrew Grant, Professor Duncan Maskell and their
groups at the Department of Veterinary Medicine. “Campylobacter
is the leading source of bacterial gastroenteritis, affecting half a
million people and killing an estimated 100 people each year in the UK,”
says Grant. “This is why it’s a major target for research efforts.”
Poultry is big business. Production units supplying the major
supermarkets can house 50,000 birds or more. Even when stringent
biosecurity measures are taken, incursions occur when barriers are
broken. “It takes just a couple of bacteria, or perhaps even one,
entering a unit for a flock of thousands of birds to be infected in less
than a week,” says Grant. “The chicken gut is the ideal vessel for Campylobacter to flourish. Transmission is guaranteed by a continual process of consumption and excretion known as coprophagy.”
There are no vaccines – either for poultry or humans – to protect against Campylobacter. The ubiquity and resilience of Campylobacter jejuni
(the strain that colonises poultry and causes most gastroenteritis in
humans) have prompted a government-led push to reduce the level of
infection by developing ways in which to contain, and ultimately
eliminate, its presence in the nation’s most popular meat.
“We need to look at the problem both on an industry-wide scale and on
a microbial scale. The first approach involves working hand-in-hand
with producers and processors and the second working in the lab to
understand the structure and behaviour of Campylobacter,” says Grant.
“Working with the industry, we’re building a picture of the highly
dynamic process of transmission from one bird to another and also at the
ways in which Campylobacter is spread during slaughtering and processing. In the lab we’re looking at how we can manipulate Campylobacter so that it can’t spread – essentially we’re trying to identify and target its Achilles heel.”
One avenue being explored is the identification of the Campylobacter
genes required for chicken colonisation, which could make good targets
for therapeutic intervention. Another approach is to disarm Campylobacter
by altering its characteristic shape from spiral to rod-shaped. Once
rod shaped it loses its ability to colonise chickens and cause disease
Scientists working on Campylobacter
face formidable challenges. Highly successful in the environments where
it thrives best, the bug is difficult to culture in the lab where
scientists need to work with live bacteria.
In the food production and retailing sectors, a reluctance to take
ownership of the problem has led to lack of investment in measures to
address an issue that each sector sees as the other’s problem. The
profit margins made by farmers are tiny – as low as one or two pence per
bird produced. The onus therefore is seen to lie with processors and
retailers to invest in intervention and control strategies.
There is a mounting sense of urgency in the drive to eliminate Campylobacter from the nation’s food chain. Incidents of Campylobacter
food poisoning are continuing to rise. Around 75,000 cases per year are
‘culture confirmed’ and, due to under-reporting, the true total is
estimated to be equivalent to at least 460,000, and possibly 750,000,
“Campylobacter found in raw chicken sold to consumers is
generally on the surface of the birds, which means that adequate cooking
quickly destroys the bacteria. But we now think that it might be
entering chickens’ muscle tissue and internal organs,” says Grant.
“Infection by Campylobacter is considered to be the most
prevalent cause of bacterial diarrhoeal disease worldwide. Compared to
many other pathogens we know comparatively little about the bacteria and
there are still many more questions than answers. There is a need for
alternative strategies to reduce Campylobacter in chickens and Campylobacter-induced disease burden in humans.”
- See more at: http://www.cam.ac.uk/research/features/c-is-for-chicken-and-campylobacter#sthash.OFd4QsOk.dpuf