Danish officials are investigating a years-long outbreak of Listeria infections that has affected nine people from 2018 through this month.
The Statens Serum Institut (SSI), Danish Veterinary and Food Administration (Fødevarestyrelsen) and DTU Food Institute are trying to find the source of the infections.
The same type of Listeria monocytogenes has been found in nine people from late 2018 to November 2021. The four patients this year have all only recently become ill. Two people fell sick in both 2018 and 2019 and one case was recorded in 2020.
Among those sick are seven women aged from 35 to 95 years old and two children younger than age 5. They live all over the country. All nine Danish patients have been hospitalized but there have not been any deaths.
Whole genome sequencing (WGS) showed samples from outbreak patients to be closely related, which means it is likely they came from the same source.