There is a current trade recall of frozen vegetables due to concerns about possible contamination with Listeria monocytogenes. The recall is a precautionary measure following an investigation in Europe of an outbreak of a specific strain of L. monocytogenes with 47 cases across 5 EU countries. The outbreak, dating back to 2015, has been linked to frozen corn and possibly to other frozen vegetables. There have been no cases of Listeria of the same type as the outbreak strain, in Queensland, in the last 18 months.
Listeriosis is a rare but serious disease with 70 to 80 laboratory confirmed cases per year in Australia. Listeriosis is caused by the bacteria L. monocytogenes that can survive and grow on certain high-risk foods. Whilst it is probably common for people to eat foods contaminated with a small amount of the bacteria without coming to any harm, significant infections can occur in individuals with compromised immune systems. Infection during pregnancy can lead to miscarriage, stillbirth or infection of the neonate.
How should we advise patients?
Consumers can return the recalled product to the place of purchase for a full refund; or compost it; or dispose of it as regular garbage. Non-ready-to-eat frozen vegetables should be thoroughly cooked.
Individuals who present with gastrointestinal illness should be investigated and managed as usual.
Pregnant women who have consumed the recalled frozen vegetable product may be concerned about their risk of infection and transmission to the infant. The risk is thought to be very low. No testing, including blood or stool cultures, or prophylactic antibiotic treatment, is recommended in asymptomatic women even if they report recent consumption of recalled product.
Pregnant women with mild gastrointestinal or flu-like illnesses should be managed as clinically indicated. In relation to Listeria, neither testing nor prophylactic antibiotics is recommended. Where concerns arise, discussion with the obstetric team may be advisable.
In pregnant women with fever and other possible symptoms of Listeria infection, investigation and management should be discussed with the obstetric team, with further specialist advice as indicated.
Invasive listeriosis in individuals with compromised immune systems generally manifests as a significant systemic illness, including sepsis and/or CNS infection. These should be managed as clinically indicated.
Australasian Society of Infectious Diseases Management of Perinatal Infections guidelines available at https://www.asid.net.au/documents/item/368. Note the recent update on the last page of the document.
Further information on listeriosis: http://disease-control.health.qld.gov.au/Condition/724/listeriosis.
Dr Margaret Young, Public Health Physician
11 July 2018