Five European countries have reported Salmonella infections with at least some of them linked to tahini and halva from Syria.
Up to 80 people may have been affected since 2019 in Germany, Sweden, Norway, Denmark and the Netherlands with several types of Salmonella being linked to the outbreak.
Based on epidemiological information and whole genome sequencing (WGS) analyses, experts from the Robert Koch Institut (RKI) in Germany told Food Safety News that they consider cases with the Salmonella serovars Mbandaka, Havana, Amsterdam, and Orion to be part of the outbreak.
Germany has 51 patients, with 49 confirmed by WGS plus two with an epidemiological link to a WGS-confirmed case. This includes 21 in 2019, 12 in 2020 and 18 in 2021.
RKI officials said they initially noted an increase in Salmonella Havana case numbers in 2019 but were unable to identify the source of infection. Those patients have been retrospectively linked to the current outbreak based on WGS results. Whole genome sequencing provides so-called fingerprints of bacteria, identifying matches between patients and specific pathogens.
Reported illness onset dates range from January 2019 to May 2021. There are a few possible people sick with onset dates in June 2021, which are not yet WGS-confirmed. The age of cases ranges from 6 months to 69 years and 53 percent are female. They live across Germany in 15 of 16 federal states.
Recall in Norway
Norway has two patients with Salmonella Mbandaka who reported eating sesame seed products. They are 5 and 45 years old, both female and from different regions of the country. Sampling dates of the isolates were March 2020 and June 2021.
Sesame seed products Al Burj Tahina and Al Burj Halwa from Syria and imported into Norway were recalled earlier this month. Best before dates range from June 2021 to January 2022.
The recall is based on detection of Salmonella in testing by Sweden and preliminary results from samples by Mattilsynet. Examinations are ongoing to see if the recalled products in Norway are contaminated with Salmonella Mbandaka.
Sweden is investigating two clusters of Salmonella Mbandaka and Salmonella Havana with 11 cases each.
In total, the 22 patients are spread across 10 different regions with the first reported in May 2019 and the latest in June 2021. The gender distribution is even and the age range is 0 to 77 years old, but 12 cases are children under the age of 5.
Investigating potential links
Sharing of sequence data from Salmonella isolates on an EU system for public health experts show a connection to previous outbreaks with a link to sesame based products.
Rikard Dryselius, a microbiologist at Folkhälsomyndigheten (the Public Health Agency of Sweden), said: “Sampling and analysis carried out by Livsmedelsverket (the Swedish Food Agency) has led to findings of Salmonella in several products of tahini and halva. The isolates of Salmonella are currently being sequenced to reveal the serotypes and if there is a connection to human cases. There are possibly also other serotypes than Salmonella Havana and Salmonella Mbandaka involved.”
Denmark has two cases of Salmonella Mbandaka that are related to the outbreak. They are from February 2021 and include one child and one adult.
The Netherlands has identified one matching Salmonella Mbandaka case based on whole genome sequencing. The affected person is a 1.5 year old child with the sample being taken on March 21 this year.
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