The source of the shigella disease outbreak has been determined

In August and September, 44 Danes fell ill due to the intestinal bacterium shigella. The investigation shows that the source of infection was likely from imported fresh mint.

Statens Serum Institut (SSI) in collaboration with the Danish Veterinary and Food Administration and DTU Food has investigated a disease outbreak caused by the intestinal bacterium shigella.

Forty-four patients were linked to this outbreak. A total of 30 women and 14 men aged 0-75 years were affected, 13 of whom were hospitalized as a result of the infection. The patients presented with symptoms in the period from 22 August through 9 September 2020. The affected people mainly reside in the Capital Region of Denmark.

Read more in EPI-NEWS 41/20

Always rinse fruit and vegetables

The epidemiological investigation of patients and outbreaks related to social events revealed that the majority of the patients had ingested fresh mint bought at local greengrocers in and around the Copenhagen area.

“Ready-to-eat fruit and vegetables should not contain pathogenic bacteria or viruses, but this may occur in rare cases. This outbreak provides an opportunity to remind citizens that fresh herbs should always be rinsed thoroughly before you eat them”, notes Epidemiologist Luise Müller, SSI.

Traceback showed that the contaminated food was probably fresh mint of foreign origin sold from mid to late August.

“The investigation indicates that mint from abroad may be the source of this outbreak. The investigation has been characterised by missing invoices among the local greengrocers. Fresh mint has a short shelf life, so luckily the mint is no longer on the market. Therefore, there is no risk that any more consumers will become infected,” explains Nikolas Kühn Hove, Head of Preparedness, Danish Veterinary and Food Administration.

Transmitted by food

Shigella, like Salmonella and Campylobacter, is an intestinal bacterium typically transmitted by food. The symptoms of shigella infection include acute intestinal infection with general malaise, diarrhoea, stomach ache and, in some cases, nausea, vomiting and/or fever. The infection is typically self-limiting. Severe infections may present as dysentery (i.e. blood, mucus and pus in the stools, fever and general malaise).

What you should do if you have ingested fresh mint

The contaminated mint is no longer available in shops. Even if you have ingested fresh mint that was bought in August or September, the risk that you have become infected with shigellosis is considered to be minimal. If you have not had symptoms consistent with shigellosis or if you have had symptoms which have passed without treatment, you do not need to do anything. In case of persisting symptoms or doubts, please see your GP.

The outbreak was investigated as a joint effort counting Statens Serum Institut, DTU Food and the Danish Veterinary and Food Administration.

Read more

Read more about shigella infection.

Read more about good kitchen hygiene (in Danish language) at the website of the Danish Veterinary and Food Administration.