Fødevarestyrelsen (The Danish Veterinary and Food Administration/DVFA) said dates were sold in Rema1000 stores throughout the country.
RM Import A/S and Rema1000 recalled certain lots of dates earlier this week. The virus has not been found in the product.
More cases expected and 16 hospitalised
Statens Serum Institut (SSI) said nine women and eight men aged 17-79 years throughout the country are affected.
They became ill from 22 December 2017 to 22 January 2018 and 16 have been hospitalized.
The agency added it expects more cases as illness onset can take up to four weeks.
Virus from seven patients has been identified as type 3A and genetic studies have shown four of these are identical which supports the theory of a common source of infection.
SSI conducted interviews with patients and did a case-control study with several of those ill saying they ate dates – a product more commonly consumed during the Christmas period in Denmark.
Results showed the source of infection was likely dates as patients had eaten this food more often than the comparable group of healthy Danes.
Eleven of 13 cases ate dates and seven people of 22 in the case control study reported eating dates. This pattern was more than any other food previously associated with Hepatitis A and fits with when the dates were on sale and the incubation period of four weeks.
It is the second national foodborne outbreak of hepatitis A in Denmark. The first was in 2013 and was linked to frozen strawberries with 68 cases (38 confirmed) in Denmark, Finland had 14 (seven confirmed), Norway seven (six confirmed) and Sweden 17 (13 confirmed).
RM Import: Our dates are not the outbreak source
RM Import A/S said it imports dates from Iran and its supplier is FSSC 22000 certified with all workers having health certificates to show they don't have diseases.
The firm told FoodQualityNews that it does not believe its dates are the source of the outbreak and they have not tested positive for the virus.
“Nine of the sick people had eaten dates within the last seven weeks. They had of course also eaten a lot of other things but the authorities concluded, after they had interviewed 22 people not being sick, that it must have been the dates,” it said.
“We have told them that we do not understand this conclusion and that we need better proof that it comes from our dates. We have to get a clear proof that our dates are the source before we can talk about [what we will be doing to ensure this does not happen again].
“For Rema1000 we have sold since October 2017 about 250,000 boxes of the 400g dates they suspect, but only nine of the sick have eaten dates. We believe that a much larger amount [would have] been sick if really the dates were the source.”
Juicy Dates dadler 400g all dates with lot numbers: L3130424; L3130425; L3130426; L3130427; L3130428; L3130507; L3130508; L3130509; L3130510; L3130511; L3130517; L3130519; L6130603: L6130615; L7130512 and L7130515 are affected.
Fødevarestyrelsen said it was suspected the source of the outbreak is Hepatitis A in dates from one or more of the above lot codes but there is no suspicion of the virus in other pack sizes, variants or batches from the same supplier.
The investigation is by the Central Outbreak Group, consisting of representatives from SSI, Fødevarestyrelsen and DTU Fødevareinstituttet (DTU Food Institute).
Many Danes have been vaccinated against hepatitis A in connection with international travel.
Other country distribution
Dates were also distributed to Germany and Norway, according to the RASFF portal.
In Norway, Bama Gruppen AS withdrew Juicy Dates 400g from Iran with best before date 10.6.2018.
The dates have batch numbers L3130429 and L3130425 and were sent to Rema1000 stores in Troms and Nordland in mid-November last year.
Hepatitis A virus (HAV) is transmitted through ingestion of contaminated food and water or through contact with an infectious person, according to the World Health Organization (WHO).
Unlike hepatitis B and C, hepatitis A infection does not cause chronic liver disease and is rarely fatal but it can cause fulminant hepatitis (acute liver failure), which is often fatal.
Hepatitis A viruses can withstand food production processes routinely used to inactivate and/or control bacterial pathogens.