An E. coli outbreak in Denmark that has affected more than 60 people in less than a month has been linked to spring onions from Egypt.

Enteroinvasive E. coli (EIEC) is usually associated with travel diarrhea but the 68 patients in the outbreak have not traveled abroad.

An investigation by the Statens Serum Institut (SSI), Danish Veterinary and Food Administration (Fødevarestyrelsen), local hospitals and the DTU Food Institute found the probable source of infection was spring onions used in ready-to-eat salads sold in three different retail chains.

From Nov. 23 to Dec. 17, 68 infections have been registered including 43 women and 25 men aged 1 to 91 years old sick with a median age of 53.

Twenty people have been admitted to hospitals and patients live across the country, except for the Nordjylland region.

EIEC has been isolated from more than 20 patients and the remaining are PCR positive for the invasion plasmid antigen H (ipaH) gene, which is specific to Shigella species and EIEC.

Establishing the source of infection
SSI has interviewed 17 patients and a common food source for 11 of them is ready-to-eat salads. Assessment of purchasing data showed the salads were bought from Nov. 15 to 30.

Six people have provided enough information for the Danish Veterinary and Food Administration to identify at least three types of salads and a Danish producer.

Officials inspected the producer and findings showed that common ingredients for all the implicated ready-to-eat salads were spring onions from a Dutch supplier but originating in Egypt.

Investigation and traceback work is ongoing to discover how the salads were contaminated with E. coli but initial results are that it didn’t happen in Denmark.

Salads were sold at REMA1000, COOP and Meny stores. They have a short shelf life of six days and potentially contaminated batches of spring onions are also thought to be no longer on the market, as delivery dates were between Nov. 16 to 30.

EIEC can cause intestinal infections and is typically seen among travelers. It is closely related to Shigella. EIEC is transmitted from person to person or through drinking and bathing water, as well as foods contaminated with human or animal feces. Microscopic amounts of feces can cause illnesses.

The time between being infected and symptoms occurring is typically one to three days. Infection can cause diarrhea, stomach pain, nausea, vomiting or a fever lasting several days and usually goes away on its own. Plenty of fluids are important to prevent and treat dehydration related to diarrhea and vomiting. In case of severe diarrheal disease, consult a doctor or go to an emergency room.

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