Food safety experts are warning the public to wash their hands after visiting the supermarket, to ward off the risk of catching the campylobacter bug.
As many as nine million packs of chicken per year are believed to carry the bacterium, which can cause fever, sickness, diarrhoea - and even death.
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And campylobacter isn't just on the inside of the wrapper, with figures two years ago showing that seven percent of chicken packaging was contaminated with the bug.
And this, say experts, means that supermarket shoppers are at risk of becoming infected before they've even got their meat home and opened the pack.
"For example, people quite often get hungry in the supermarket and may buy snacks such as crisps to eat on the way home," Dr Lisa Ackerley, an independent food hygiene expert, tells the Daily Telegraph.
"But if they've picked up chicken with bacteria on the outside packaging and licked their fingers they could consume enough bacteria to become ill."
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Over the last couple of years, many supermarkets have tightened up their procedures to try and cut the risk of campylobacter contamination.
The Co-op, for example, announced that it would only sell whole chickens in roast-in-the-bag packaging, meaning there's no need for consumers to touch the meat directly.
However, an analysis by the Daily Telegraph indicates that 1.1% of supermarket chickens have a medium or high level of campylobacter on the outside of the packaging - potentially a high enough dose to cause illness, it says. And with around 650 million chickens sold in the UK every year, that represents as many as nine million birds.
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In its latest figures, the Food Standards Agency has not broken down infection levels by retailer, as it has done in the past - meaning that consumers no longer know which supermarkets have the highest or lowest levels of the bug.
However, in 2015, Asda chickens were found to have the highest levels of campylobacter on the outside of their packaging, at a worrying 12.4%, followed by Morrisons at 11.2%. M&S had the least contaminated packs, at just 2.9%, followed by Tesco at 4% and Sainsbury's at 4.9%.