Listeria Continues To Present Problems.


Only a week following the declared end of the extensive Listeria outbreak in the Republic of South Africa, the European Center for Disease Prevention Control and the European Food Safety Authority have reported on an outbreak of listeriosis involving 47 cases with nine fatalities in Scandinavian nations, Austria and the U.K.

Whole genome sequencing has implicated frozen corn as the vehicle of infection. The pathogen has been identified as Listeria monocytogenes IVb sequence type ST6 similar to the strain associated with outbreaks implicating frozen spinach and frozen green beans derived from a plant in Hungary. Production at the plant has been suspended pending further investigations and thorough decontamination as required.

The outbreak strain of Listeria monocytogenes was detected in frozen vegetables in both 2016 and 2017 before the current episode, suggesting that the pathogen has persisted in the plant in Hungary, which is not unusual for Listeria.

The specific vegetable responsible for outbreaks has not been clearly identified suggesting that only the outbreak strains from patients are homologous with the environmental samples from the plant and not from products. Eleven of 26 patients from Denmark, Finland, Sweden and the U.K. reported consuming frozen corn and six out of 15 apparently ate frozen mixed vegetables.

Identifying a source of infection is problematic with an infection characterized by an extended incubation period resulting in consumers failing to recollect what food items were consumed over a protracted period.

Labeling, especially in a multilingual market such as the E.U. frequently does not emphasize the distinction between ready-to-eat items and those that require cooking. This exposes consumers to potential food-borne bacterial infection