Two recent Campylobacter outbreaks traced to poultry meat in Denmark highlight the issues with current regulations, according to scientists.
In July to November, two Campylobacter jejuni outbreaks with 119 reported patients were detected through Denmark’s whole genome sequencing surveillance program. They were clinically severe as 45 people were hospitalized and 16 had bacteremia.
Researchers estimated there were 900 laboratory-confirmed outbreak cases with 670 in the first outbreak and 238 in the second. Both outbreaks originated from Danish-produced chicken meat.
Beginning in January 2025, EU rules state that no more than 10 of 50 carcass samples can exceed 1,000 colony forming units per gram (CFU/g). If this happens, there needs to be improvements in slaughter hygiene, a review of process controls, and of biosecurity measures in the farms of origin.
Severe outbreaks
In Denmark, around 5,000 lab-confirmed Campylobacter cases are notified yearly through the national surveillance system. Since 2019, Statens Serum Institut (SSI) has performed national WGS-based surveillance, covering 10 to 15 percent of confirmed cases. Bacterial genomes from cases are compared with genomes from the Danish Veterinary and Food Administration’s (DVFA) surveillance of food and animal sources.
According to the study published in the journal Eurosurveillance, both types had been detected in patients and Danish-produced chicken meat in previous years.
In total, 89 isolates were assigned to the first outbreak and 30 to the second. In the first outbreak, patients aged 4 to 89 were sick. Thirty people were hospitalized. In the second outbreak, people aged 2 to 90 fell ill and 15 were hospitalized.
Researchers said the high proportion of bacteremia challenged the perception of campylobacteriosis as a generally mild, self-limiting disease. They added that severe disease can occur despite the routine monitoring and control measures in poultry production.
Consumer burden
Sequencing confirmed that the clones matched concurrent isolates from Danish chicken meat identified by DVFA, establishing this as the source of each outbreak.
From 35 patient interviews, all of them reported eating chicken meat during the week before symptom onset.
Scientists said the two unusually severe and large outbreaks within a short period reveal the vulnerability of the current prevention and control framework for poultry.
“In the absence of legal prohibition against Campylobacter in fresh, frozen or marinated chicken meat, this framework places much of the practical burden of Campylobacter risk reduction on consumers through safe food handling practices. The described outbreaks reveal a misalignment between surveillance and current regulation targets,” the report says.
