Norwegian public health officials are investigating an outbreak of hepatitis A that has affected 10 people.

The Norwegian Institute of Public Health (FHI) reported an investigation has been started with local health services and the Norwegian Food Safety Authority (Mattilsynet) but the suspected source is unknown.

Infection has been detected in 10 people living in several counties. Another two people are suspected of being part of the outbreak.

Samples were taken from April to September and sequencing shows hepatitis A virus (HAV) with an identical sequence of genotype 1A in all of the patients. This suggests they were infected from the same source.

Sick people are between 25 and 80 years old with a median age of 53. Sixty percent are men.

Widely distributed food suspected

Six patients live in Viken, two in Trøndelag and one each in Oslo, Vestfold og Telemark, Innlandet and Troms og Finnmark.

“None of those infected have traveled abroad. Based on where they live, it is likely that they are infected through a food that is widely distributed,” said Heidi Lange from FHI.

Patients are being interviewed about what they ate or drank before becoming ill. The time from a person becoming infected with hepatitis A until symptoms develop can be from two to six weeks, but is usually around four weeks.

The most recent outbreak of hepatitis A in Norway, in 2014, was linked to frozen berries. The Norwegian Food Safety Authority advises that people boil frozen berries for one minute before using them in recipes that are not heat treated.

Hepatitis A is spread when someone ingests the virus through close contact with an infected person or by having contaminated food or drinks. Symptoms include inflammation of the liver, fever, low appetite, nausea, vomiting, diarrhea, muscle aches, and yellowing in the whites of the eyes and the skin (jaundice).

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