The number of Campylobacter infections in Denmark has increased for the third year in a row.

In 2019, the amount of registered Campylobacter infections increased by almost a fifth. A total of 5,389 illnesses were registered, which is an 18.5 percent rise on the 4,547 cases in the previous year.

The increase is because of a large outbreak traced to Danish chicken meat. This food was also determined to be the source in five other outbreaks, while the source was unknown in three other outbreaks. The remaining Campylobacter cases in 2019 are recorded as sporadic.

The data comes from the 2019 annual report on the incidence of zoonoses by the National Food Institute, Technical University of Denmark, Statens Serum Institut and Danish Veterinary and Food Administration (Foedevarestyrelsen).

A previous SSI report found there was a high incidence among young adults in their 20s in 2019 and the Campylobacter rate among elderly people older than 85 and in men was higher than previously observed. Among young children of 0 to 4 years, the incidence was lower than seen before.

Of all cases in 2019, 1,928, or 36 percent, were acquired abroad. Turkey accounted for the most registered infections closely followed by Spain with Thailand, Indonesia, India, France and Morocco also on the list.

A study in the journal Scientific Reports recently warned in the future that nearly 6,000 excess Campylobacter cases per year in the four Nordic countries could be linked to climate changes.

Infections often part of outbreaks and traced to chicken
During 2019, Statens Serum Institut and the Danish Veterinary and Food Administration analyzed and compared Campylobacter from patients and Danish chicken meat. Data show that cases are more often related to outbreaks than previously thought. Findings show almost one third of all patients have a Campylobacter infection that can be attributed to chicken meat.

Many Campylobacter infections in Denmark are not sporadic and can be linked to outbreaks, according to a study published in Emerging Infectious Diseases.

Eva Møller Nielsen, head of unit at Statens Serum Institut, said the new knowledge provides opportunities to prevent infection in Denmark.

“We are surprised that analyses of patient samples using whole genome sequencing show that the Campylobacter cases to a greater extent are part of outbreaks, which can be traced back to the same food source, and that the majority of these outbreaks can be attributed to chicken,” said Nielsen.

Industry has started initiatives aimed at reducing the occurrence of Campylobacter in the food production chain. An expert group led by the European Food Safety Authority (EFSA) has assessed various options for controlling infection in the production of broilers.

“Given that we in the expert group have not found one single solution to solve the problem, it is paramount that authorities, the industry and researchers have access to reliable data, which can guide efforts to reduce the incidence of illness in humans,” said Johanne Ellis-Iversen, head of research group and senior advisor at the National Food Institute.