The percentage of chickens positive at the highest level of Campylobacter contamination in the United Kingdom has increased, according to the latest figures.

For the top nine retailers, 3.5 percent of fresh whole chicken samples tested from January to March 2019 carried more than 1,000 colony forming units per gram (cfu/g) of Campylobacter.

The figure for previous results from October to December 2018 was 3.1 percent, for July to September it was 3.5 percent while for April to June it was 3.7 percent.

Campylobacter is the most common cause of food poisoning in the U.K. with an estimated 280,000 cases annually. The infectious dose can be as low as a few hundred cells.

Percentage and levels of contamination

Latest rates show 15.8 percent of birds were positive in the 100-1,000 cfu/g category compared to 11.4 percent from October to December 2018, 11 percent from July to September and 12.5 percent from April to June.

The cfu/g 10-99 category had 25.3 percent of chickens positive for Campylobacter compared to 22.3 percent in October to December 2018, 26.7 percent in July to September and 23.3 percent in April to June.

In the lowest category, cfu/g less than 10, 55.4 percent of chickens were positive, compared to 63.1 in the last set of results, 58.8 percent from July to September and 60.6 percent in April to June.

Comparing January to March 2019 against the same period in 2018 shows birds positive at the highest level declined slightly while rates in the other three cfu/g brackets increased.

Rebecca Sudworth, director of policy at the Food Standards Agency, said the rate at the highest contamination level are better than the agency’s targets.

“Campylobacter levels have remained steady and are below our target of 7 percent at the highest level of contamination. Nevertheless, we will continue to work closely with retailers to bring levels down to as low as reasonably achievable. Our advice to consumers remains the same: take care when handling raw chicken, do not wash it, and ensure it is cooked thoroughly before serving.”

Decline for Co-op, Lidl and Waitrose

Marks and Spencer recorded 6 percent in the highest category in January and 2 percent in both February and March based on samples from 278 chickens. That compared to 4 percent in October; 2 percent in November; and 1 percent in December, based on 335 samples. Tesco data showed the percentage at this level doubled to 6 percent of 362 samples versus previous results based on 524 samples.

Aldi reported 5 percent of birds in the more than 1,000 cfu/g category from January to March 2019, doubling the percentage in this range based on the last set of results. Asda had 5.5 percent in this bracket which was higher than the 5.1 percent figure of previous results.

Morrisons results from January to March are 5.4 percent of 111 chickens at the highest level of contamination compared to 1.8 percent from a sample of 113 in the previous results.  Sainsbury’s results stayed the same as the last quarter with 1 percent of chicken samples at the highest level.

Co-op results for Q1 2019 showed 0.9 percent of chickens sampled had contamination at levels greater than 1,000 cfu/g compared to 2.7 percent in Q4 2018. Lidl recorded 1.5 percent which was down from the previous 5 percent figure.

For the first quarter of the year, 2 percent of Waitrose and partners chickens tested positive for Campylobacter at more than 1,000 cfu/g compared to 5 percent in the previous results.

A Waitrose and partners spokesperson said data gathering and analysis included surveying chicken at the factory and on supermarket shelves.

“We are delighted that our results remain well below the FSA target of 7 percent or fewer samples testing more than 1,000 cfu/g. Our testing regime is rigorous and because we know the prevalence of Campylobacter is reduced over a product’s shelf life we have ensured our sampling is random and adhered to the FSA testing protocol throughout the survey.”