Sweden has been hit by two different outbreaks of E. coli, with one of them affecting more than 100 people. A pizza ingredient is suspected, but investigations are ongoing.

An outbreak of E. coli O157:H7 has 105 confirmed cases while 13 people have been infected with E. coli O26.

A spokeswoman for Folkhälsomyndigheten (Public Health Agency of Sweden) told Food Safety News it hopes that both enterohemorrhagic E. coli (EHEC) outbreaks are over, with the latest illness onset date being in August.

EHEC is also known as Shiga toxin-producing E. coli (STEC) or Verocytotoxin-producing E. coli (VTEC).

The majority of patients in the E. coli O157 outbreak fell ill in July with the latest case reported on Aug., 23.

Thirteen regions have reported infections: Västra Götaland, Uppsala, Kalmar, Halland, Skåne, Östergötland, Västernorrland, Stockholm, Gotland, Sörmland, Gävleborg, Kronoberg and Jämtland.

About 10 percent of cases have developed Hemolytic Uremic Syndrome (HUS), a type of kidney failure. Folkhälsomyndigheten said this could be expected due to the more virulent EHEC strain.

There are also five infections with an epidemiological link to confirmed cases as they are Shiga toxin (stx) 2-positive in PCR testing but EHEC was not isolated.

A case-control study is ongoing but a preliminary analysis shows the sick people were more likely to have eaten at pizzerias compared to controls. Further tracing has not identified the vehicle of infection. Officials suspect a food distributed to several pizzerias but also to restaurants or grocery stores as not all meals were eaten at pizzerias.

Livsmedelsverket (National Food Agency) told us it does not know if the food source is imported or domestic.

“We have performed back tracing of food from the pizzerias, but the results are not conclusive. We tested some samples of different food types from one of the pizzerias with negative results,” said the agency.

The E. coli O26:H11 stx1a outbreak was identified through the national microbial surveillance program at Folkhälsomyndigheten. The source of infection is unknown but suspected to be foodborne.

Thirteen cases from seven different regions: Gävleborg, Halland, Kalmar, Uppsala, Västra Götaland, Örebro and Östergötland are confirmed as belonging to the outbreak.

The infected people, eight women and five men, are between the ages of 15 and 83 and fell ill between July 19 and Aug., 16.

One case has developed HUS and is also infected with EHEC O26:H11 stx2a which is not seen in the other cases.

In recent years, Sweden has had between 35 to 85 domestic cases of EHEC O26 annually.

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