Fresh basil imported from Israel is the prime suspect in an outbreak of shigellosis, according to Norway’s Food Safety Authority (NFSA).

On October 10th, NFSA announced that several residents of Tromsø were suffering from shigellosis after becoming infected with Shigella sonnei – a microbe that usually is transmitted through contaminated water or food. As of today (November 1st), 46 outbreak cases have been confirmed – 42 in Tromsø and 4 in Østfold.

Most of the illnesses were reported in early October, with the last onset date having been recorded in mid-October.

Shigella outbreak onset dates

When interviewed, 36 of the outbreak patients reported having eaten pesto, and an additional three victims said that they had been served fresh basil – an ingredient in pesto. Patient interviews pointed to pesto made by a Tromsø catering company as a possible source of the infections.

Basil imported from Israel by Bama and supplied to the Tromsø company was used to make the pesto. Bama also supplied basil from the same batch to an Østfold restaurant where three of the four Østfold outbreak victims had eaten a few days before becoming ill.

Based on the epidemiological and tracing results, Bama has halted all sales of Israeli basil until further notice. Basil has a short shelf life, and the shipment that was implicated in this shigellosis outbreak is no longer in the marketplace.