Danish research organisation Statens Serum Insitut (SSI) reported that 27 patients have contracted Hepatitis A (HAV) from eating Iranian-produced Juicy Dates.

The number of known cases has gradually increased since December 2017. It is reported that 15 women and 12 men, of a median age of 65, have been infected in total. Of those infected, 18 patients contracted the virus subtype 3A, suggesting that all the cases were closely related.

The SSI conducted a study in an attempt to pinpoint the exact cause of the outbreak. In the study, 19 participants who were infected responded to questions over the food they ate since December. The control group consisted of 54 participants who had not contracted HAV.

Among the first group, 89% said they had eaten dates compared with 28% in the control. This result, combined with the fact that date sales increased over the Christmas period and the disease appeared four weeks later, was enough for the SSI to make the connection.

The long shelf-life of the dried fruit means that the product is consumed over a long period and HAV takes around four weeks to exhibit symptoms.

Of those who became sick, 23 people said they ate dates during this period and most suggested they bought their dates from multinational supermarket chain REMA 1000. Seven of those questioned said that the products were made by Iranian date manufacturer Juicy Dates.

The Danish Veterinary and Food Administration department (Fødevarestyrelsen) found that Juicy Dates were being sold in the Danish Supermarket and ordered the importer RM Import to recall the dates in early February.

RM Import denied that the dates caused the HAV illness, saying its supplier is Food Safety System Certification (FSSC) 22000 certified.

Date samples were taken from three patients’ homes and analysed using DNA testing. All samples were found to be negative for HAV. The SSI responded that testing for HAV in food is challenging, and a negative result did not conclusively mean the samples were clean.

“With the increasing international trade in fresh and frozen foods, including fruit and vegetables from countries where HAV is endemic, the risk of infection increases through the consumption of HAV-contaminated foods,” an SSI spokesperson commented.

One case of HAV infection in Norway exhibited the same subtype (A3) as the Danish patients.

Norwegian fruit and vegetable distributor Bama Gruppen withdrew Juicy Dates from Rema1000 stores in February.

This is the second HAV outbreak in the Nordic countries, the first reportedly caused by frozen strawberries in 2012-13.