Authorities in Norway are investigating a Salmonella outbreak that has affected nine people.

The Norwegian Institute of Public Health (Folkehelseinstituttet) said the patients became ill in January and early February. They are aged from 2 to 91 years old. The agency is investigating with local authorities, the Veterinary Institute (Veterinærinstituttet) and the Norwegian Food Safety Authority (Mattilsynet).

Five men and four women have been confirmed infected with Salmonella Agbeni. They live in Oslo, Akershus, Buskerud, Rogaland and Vest-Agder. Bacteria with a similar DNA profile has been detected in all nine people, which strongly suggests a common source. Officials are interviewing patients and sampling food leftovers to find the infection vehicle.

Officials from the Norwegian Institute of Public Health said such investigations can be complicated and take time with no guarantee the source of infection will be found. They added it was too early to say whether it is a limited outbreak or whether additional patients will be identified.

Every year, 900 to 1,300 cases of salmonellosis are reported to the Norwegian Institute of Public Health, with most people infected while traveling abroad.

Salmonella Agbeni was not in the list of the 20 most frequent serovars in confirmed cases of human salmonellosis in Europe meaning there were fewer than 265 infections in 2017, according to data from the European Food Safety Authority (EFSA).

Earlier this year, the United States concluded an investigation into a Salmonella Agbeni outbreak associated with Duncan Hines cake mixes. Seven people across five states were infected with the outbreak strain. Conagra Brands recalled four varieties of Duncan Hines cake mix in November 2018.

People can experience symptoms of Salmonella infection between six and 72 hours after exposure and these usually last for three to seven days. They include fever, diarrhea, vomiting, headaches, stomach cramps and loss of appetite. More severe symptoms may occur in young children, older people, pregnant women and people who are immunocompromised.

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