Campylobacter bacteria found in most chicken livers sold in Japan
What it found
Campylobacter was found in 81.8% of vacuum-packed chicken liver products bought from shops in Japan.
The bacteria were also present inside the livers and bile of chickens at processing plants.
What they found
Animal and lab studies
Bacteria in chickens at plants
In 35 chickens tested at processing plants, Campylobacter was found in the guts of 27 (77.1%). Of those 27 birds, 24 (88.9%) had it in their livers with an average count of 2.8 log10 CFU/g. Bile from 13 of those 24 birds (54.2%) also carried the bacteria, averaging 3.5 log10 CFU/mL.
Other findings
Bacteria in shop-bought livers
Campylobacter was found in 27 of the 33 products (81.8%). Looking at individual livers from those 27 products, 138 out of 149 (92.6%) carried the bacteria. The average count was 2.3 log10 CFU/g, and 22 of the 138 positive livers (15.9%) had counts above 3.0 log10 CFU/g.
Uneven contamination within packs
Within the same vacuum pack, some individual livers had over ten times more bacteria than others. Some packs even contained a mix of positive and negative livers. This suggests the bacteria are unevenly spread inside the meat itself.
Two lab methods compared
The researchers tested 214 samples using both a standard plate method and an automated counting machine. For the 159 samples where both methods found Campylobacter, the results matched closely with a correlation coefficient of 0.93.
What the authors conclude
- They conclude that chicken livers from birds carrying Campylobacter become contaminated during processing at the plant.
- They advise that chicken livers must be heated thoroughly all the way through before eating to prevent food poisoning in people.
How it was done
Chicken liver is a known source of Campylobacter food poisoning in people. The authors wanted to measure exactly how many of these bacteria are present in chicken livers sold to shoppers and in chickens at processing plants.
They bought 33 vacuum-packed chicken liver products from shops and online stores in Japan between 2019 and 2021, testing 179 individual livers. They also collected gut, liver and bile samples from 35 chickens at two processing plants in 2020. They measured the number of Campylobacter bacteria in all samples using two different lab methods.
What it can’t tell you
- This survey only measured bacteria levels in Japan, so it cannot show what contamination levels are like in other countries.
- Counting bacteria on food does not directly measure how often people get sick from eating it.
The paper
- Title
- [Quantitative Survey of Campylobacter on Chicken Livers in Japan]
- Type
- Study
- Evidence
- Animals and lab studies
- Summarised from
- Full text
- Cite
- Sasaki Y, Yonemitsu K, Momose Y, Uema M (2023). [Quantitative Survey of Campylobacter on Chicken Livers in Japan]. Shokuhin eiseigaku zasshi. Journal of the Food Hygienic Society of Japan. doi:10.3358/shokueishi.64.214Free full textPubMed 38171891DOI
Summary written 30 Sep 2026. Check it against the paper before it changes what you eat. How we summarise papers · Report an error