Six people in Norway have fallen ill in recent months with the source of infection thought to be contaminated raw milk cheese from France.
The foodborne outbreak was suspected to be caused by Salmonella Dublin in chilled cheese made with unpasteurized milk.
The Norwegian Institute of Public Health (Folkehelseinstituttet) investigated the outbreak with the Norwegian Food Safety Authority (Mattilsynet) and Norwegian Veterinary Institute.
Link made in patient interviews
Early this year, Norwegian officials detected a cluster of six patients with Salmonella Dublin infections. Salmonella Dublin is rare in the country with typically no more than five infections reported annually, according to health officials.
Patients lived in four different counties. Their median age was 70 and a half years old with a range from 40 to 85 and half were female. Symptom onset ranged from the end of December 2020 to beginning of March this year.
In interviews, five of six people said they may have eaten raw milk cheese from France. No microbiological analysis of cheese could be performed because there was no stock left and the product is believed to no longer be on the market.
All six patients were interviewed with a standardized questionnaire for Salmonella to get food consumption history one week before symptom onset. There was also a more targeted questionnaire with pictures of different cheeses. People were also asked where they bought the different products.
Based on results of patient interviews and traceback information, raw milk cheese from France may be the source of the outbreak, but given the small number of confirmed cases and limited information, officials were unable to determine the link conclusively.
Dried product sampling results
Meanwhile, the Norwegian Food Safety Authority has published findings of a survey on dried products in the domestic market that were analyzed for Salmonella.
The surveillance program in 2020 was done to assess the sector following a Salmonella outbreak in 2019 where 58 people became ill after eating a mixture of exotic dried fruit.
Some products were ready to eat food that are often consumed without heat treatment. Salmonella survives for a long time in dry foods and can be unevenly distributed in them.
In total, 543 samples of spices, dried berries, fruit and nut mixtures, and milk powder and dried infant formula were collected and more than 1,000 analyzes done but no Salmonella was detected.
Samples were taken randomly from across the country and at all stages of the supply chain from importers and manufacturers to retailers. Products originated from many countries including the United States, China, India, Thailand, Vietnam, Denmark, Sweden, and Turkey.
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