Norwegian authorities are investigating an outbreak of E. coli where four people have developed hemolytic uremic syndrome.

The Norwegian Institute of Public Health (Folkehelseinstituttet) has identified the same type of Enterohaemorrhagic E. coli (EHEC) in three people since August and investigations are ongoing for two other cases.

The outbreak is caused by Shiga toxin-producing E. coli O?: H2 (stx2a, eae, ehxA) infection as no O-group has been identified.

The STEC pathotype is defined by the presence of the genes encoding Shiga toxin (Stx) type 1, type 2, or both. Stx2a is associated with causing severe disease. The E. coli attachment and effacing (eae) gene produces the virulence factor intimin. When present with stx2a there is a strong association with the risk of HUS. The enterohaemolysin gene (ehxA) is another virulence factor.

EHEC can also be called Shiga toxin-producing E. coli (STEC) or Verocytotoxin-producing E. coli (VTEC).

An outbreak investigation has been started with the relevant municipal agencies, the Veterinary Institute and Norwegian Food Safety Authority (Mattilsynet) as the source is unknown.

One child and four adults ill

Patients live in Hordaland, Aust-Agder, Trøndelag, and Hedmark. One child and four adults over 70 years of age are sick. Four people have developed hemolytic uremic syndrome (HUS), a type of kidney failure associated with E. coli infection.

Bacteria with similar DNA profiles have been detected in three patients, while analysis for the other two cases is ongoing. Similar DNA profiles indicate that people have a common source of infection.

Interviews have been conducted to identify whether the patients have a common source of infection. Audits of places such as catering establishments have been done in an attempt to reveal a possible source of infection.

The DNA profile of the bacteria in the outbreak has not been seen in Norway before. The Norwegian Institute of Public Health has contacted international partners to see if other countries have been affected.

In 2018, 494 EHEC infections were reported to the Norwegian Institute of Public Health but only eight developed the serious complication of HUS.

Symptoms of E. coli infection include abdominal cramps and diarrhea that can become bloody. Fever and vomiting may also occur. The incubation period can range from three to eight days and most patients recover within 10 days.

E. coli is transmitted to humans primarily through consumption of contaminated food, such as raw or undercooked ground meat, raw milk, and raw vegetables and sprouts.

Earlier this month, Guri Aanderud, of the Norwegian Food Safety Authority, told Food Safety News about seaweed from China that caused more than 100 cases of gastroenteritis from at least 11 eateries in different areas of the country.

The first outbreak of norovirus linked to the seaweed salad occurred in mid-June and the most recent one was at the beginning of August. Norovirus was detected in patients from at least two of the eateries.

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