The source of a 7-year listeria epidemic was found in Germany

German officials believe they have resolved a seven-year listeria outbreak that included the death of one man.

Using next-generation sequencing (NGS) methods, the Bavarian State Office of Health and Food Safety (LGL) helped identify a possible link between Listeria infection in Lower Bavaria and the Altötting region since 2015 and the food company.

The authorities did not name the company, but they described it as a small business in the Passau area with various clients in the area. Local media reported that it was a production company that supplied canteens and care homes but not retailers.

Besides the results of the NGS analysis, there are indications of an epidemiological link with patients based on the sales region.

Low level of disease over many years
In 13 cases of illness in Lower Bavaria and Altötting, including the death of an 85-year-old man in 2015, the same type of Listeria monocytogenes was detected, suggesting a common source of infection.

Two cases were reported in 2015, one in 2016, two in 2017, one each in 2018, 2019 and 2020, four in 2021 and one in 2022.

Recently, this type of Listeria was discovered in the company’s suspected operations. Previous surveys of patients and investigations by authorities did not find the food category responsible for the disease.

When LGL reported the results of the analysis to the local authority, officials halted operations at the company on June 24 and ordered the products to be returned with further testing at LGL and continued investigations by local authorities.

In early 2020, a look at human isolates using NGS by the Robert Koch Institute (RKI) found that a few cases of listeriosis per year in different regions in Lower Bavaria and Altötting from 2015 to 2019 were associated. Up until this point, they were thought to be isolated cases, unrelated to each other.

In cases where a small number of people are affected over many years, it can be difficult to find a common source because questioning patients is difficult due to factors such as the long incubation period, age of the patient, and the variety of foods mentioned.

Only when a link is suspected by isolating patients, can consumption habits be compared and suggestions for a possible food source identified.

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