Half a dozen people are sick in an ongoing E. coli O157 outbreak in Denmark.

Since late March, six E. coli O157:H7 patients have been identified, and one person has developed hemolytic uremic syndrome (HUS). HUS is a severe complication associated with E. coli infections that causes kidney failure. While the first case was in March, the other five occurred in September.

Five people have been hospitalized, but no deaths have been recorded, said the Statens Serum Institut (SSI).

Those sick live across the country, including three in Hovedstaden and one in Syddanmark, Sjælland, and Midtjylland.

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The patients are five men and one woman between the ages of 2 and 35.

The SSI, Danish Veterinary and Food Administration (Fødevarestyrelsen), and DTU Food Institute are investigating the outbreak.

SSI work includes the whole genome sequencing (WGS) of isolates from patients and interviews with sick people or their relatives to identify a possible source of infection.

The outbreak strain is O157:H7 sequence type 11 and is positive for the Shiga toxin (Stx) 2a subtype, which is known to be associated with severe disease and HUS.

In 2022 Denmark had 1,330 cases of E. coli, up from 927 in 2021. This rise is partly due to a change in diagnostic methods and more testing. When information on the type was known, it was O157 on 47 occasions, followed by O26, O103, and O146.

It is unrelated to the E. coli O157 outbreak reported in Norway in June. This incident affected six people, but no one developed a serious illness. Two people fell ill in October and November 2022, while the remaining four became sick in February, March, and May this year. They were aged between 14 and 49, and five were men.

about E. coli infections
Anyone who has developed symptoms of E. coli infection should seek medical attention and tell their doctor about their possible food poisoning. Specific tests are required to diagnose the infections, which can mimic other illnesses.

The symptoms of E. coli infections vary for each person but often include severe stomach cramps and diarrhea, which is often bloody. Some patients may also have a fever. Most patients recover within five to seven days. According to the U.S. Centers for Disease Control and Prevention, others can develop severe or life-threatening symptoms and complications.

about 5 to 10 percent of those diagnosed with E. coli infections develop a potentially life-threatening kidney failure complication known as a hemolytic uremic syndrome (HUS). Symptoms of HUS include fever, abdominal pain, tiredness, decreased frequency of urination, small unexplained bruises or bleeding, and pallor. 

Many people with HUS recover within a few weeks, but some suffer permanent injuries or death. This condition can occur among people of any age but is most common in children younger than five years old because of their immature immune systems, older adults because of deteriorating immune systems, and people with compromised immune systems such as cancer patients. 

People who experience HUS symptoms should immediately seek emergency medical care. People with HUS will likely be hospitalized because the condition can cause other severe and ongoing problems such as hypertension, chronic kidney disease, brain damage, and neurologic problems.