In a follow-up on the Salmonella Agona outbreak affecting Norway, the Institute of Public Health now reports 42 people infected living in several counties, with a peak in mid-November. The source of infection is currently unknown.
Outbreak investigation takes time and is demanding. Unfortunately, we are not always able to find the source of the infection. It is still early in the investigation, so all possibilities are being kept open and much work remains to be done. We are following the situation closely, says senior advisor at FHI Heidi Lange.
Although there is a jump from 31 to 42 infected people in the reporting from Monday 28 November, it does not mean that the 11 last reported people in the outbreak have been infected recently. There is a lag in reporting. All 42 infected people have been diagnosed with infection in the period 7–25 November, with a peak on 15–16 November. November, says Lange.
The infected are aged 1–88 years, the median age is 36 years and 19 of them are women. Bacteria with the same genetic profile have been detected in 29 out of 42 infected people. For the remaining 13, the sequencing results (results from investigations in the laboratory) are not yet clear.
The persons live in Vestland (13), Viken (12), Telemark and Vestfold (7), Innlandet (3), Trøndelag (2), Troms and Finnmark (1), Møre and Romsdal (1) and Oslo (3). No infected people have been reported from new counties since Monday 28 November.
17 of those infected have been hospitalized with salmonellosis. Typical symptoms of salmonellosis are diarrhea, 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 advisor 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, she adds.
Salmonella Agona has previously been detected in Norway, but then only as isolated cases and often related to infection abroad.
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