A national outbreak of Salmonella in Sweden has been linked to eating a brand of crayfish.
Folkhälsomyndigheten (Public Health Agency of Sweden) reported the probable source of infection in an update to the initial outbreak announcement.
With the help of whole genome sequencing, 31 ill people have been identified in the outbreak of Salmonella Newport.
They live in 12 counties and fell ill from July 31 to October 30. People aged one to 82 years old have been affected but it is primarily adults who are ill. Slightly more women, 18, than men, 13, have become sick
Product testing
ICA, a retailer in Sweden, has recalled ICA Large Crayfish because of suspected Salmonella, but product testing so far has been negative for the pathogen.
Local disease control units, Livsmedelsverket (Swedish Food Agency) and Folkhälsomyndigheten are investigating the outbreak.
Folkhälsomyndigheten has conducted a case-case study to help identify the potential source of infection. In this work, Salmonella cases that do not belong to the outbreak are used as controls to identify what the outbreak cases have eaten to a greater extent than the control group.
The analysis shows that it was 28 times more common that the outbreak patients had eaten crayfish compared to the control group. Most of those ill ate crayfish from ICA but other brands have also been mentioned.
Recalled crayfish
ICA was informed by Folkhälsomyndigheten that the large crayfish is considered to be the cause of a number of cases of Salmonella.
The retailer has randomly checked the Chinese crayfish it has in stock and did not detect Salmonella bacteria but withdrew all packages for precautionary reasons.
All best before dates of ICA large crayfish 700 grams is affected and the product may have been sold in stores throughout the country.
In Sweden, between 2,000 and 3,000 Salmonella cases are reported per year, of which about three-quarters are infected abroad. Between 2012 and 2018, only 95 domestic cases of Salmonella Newport in Sweden have been recorded.
A total of 33 people are sick in Sweden and several other European countries in another outbreak from a rare strain of Salmonella. Salmonella Mikawasima infections have been linked by whole genome sequencing but the source of infection is not yet known.
Those sick live across 12 counties. The most recent known date of illness onset is Oct. 24. Patients have been reported in all age groups with a range of 4 to 89 years old. Slightly more women than men are ill.
Salmonellosis symptoms include fever, headache, diarrhea, abdominal pain, nausea and vomiting. They usually start around six to 72 hours after contaminated food is eaten and last for four to seven days, but can continue for longer. Older adults, infants, and people with weakened immune systems are more likely to develop severe illness.
(To sign up for a free subscription to Food Safety News, click here.)
