Norway’s Institute of Public Health, or Folkhälsomyndigheten (FHI) discovered a national outbreak caused by the gastrointestinal bacterium Salmonella Agona. So far, infection has been detected in 31 people living in several counties. The source of infection is currently unknown.
FHI has launched an outbreak investigation in collaboration with local municipal chief medical officers, the Norwegian Food Safety Authority and the Veterinary Institute.
All 31 people were diagnosed with infection in November 2022. They are aged 1–84 years, the median age is 31 years and 18 of them are women. Bacteria with the same genetic profile have been detected in 3 of the infected. For the remaining 28 infected, the sequencing results (results from examinations in the laboratory) are not yet clear.
The persons live in Vestland (11), Viken (8), Telemark and Vestfold (5), Innlandet (2), Trøndelag (2), Troms and Finnmark (1), Møre and Romsdal (1) and Oslo (1). 13 of those infected have been hospitalized with salmonellosis. Typical symptoms are diarrhoea, headache, abdominal pain, nausea and possibly fever. Salmonella bacteria are mainly transmitted through food.
Salmonella Agona is a rare serovariant of Salmonella in Norway and the rest of Europe, so based only on the serovariant and the fact that the samples were taken in November, we assume with great certainty that the infected belong to the outbreak, says senior adviser at FHI Heidi Lange.
– The number of people admitted to hospital in this outbreak is high, but we have no indication that this salmonella variant causes more serious illness than other salmonella variants. This is probably rather an expression of the fact that it is the people admitted to hospital who are discovered, and that those with a milder infection do not see a doctor, says Lange.
– Salmonella infection usually goes away on its own without treatment, she adds.
It is currently unknown what the source of infection is, but it is common for gastrointestinal bacteria to become infected through food. FHI collaborates with the municipal health service, the microbiological laboratories, the Norwegian Food Safety Authority and the Veterinary Institute to map whether the infected may have a common source of infection.
– The people who have been diagnosed with the bacteria live in 8 counties. It is therefore likely that they are infected through a food product that is distributed throughout the country. They are now being interviewed to assess whether they may have a common source of infection, says Lange.
– It is too early to say whether this is a limited outbreak or whether it will increase in scope, and whether we will be able to find the source of infection. We are following the situation closely, she adds.
Salmonella Agona has previously been detected in Norway, but then only as isolated cases and often related to infection abroad.