NICD Statement on the Listeriosis Outbreak

As the country’s national public health institute, the NICD has played a pivotal role in the Listeria outbreak investigation. Subsequent to the identification of the source of the outbreak, there has been intense interest from many sectors for more information. This memo is to clarify the role of the NICD going forward.


The NICD is a technical organisation responsible for performing epidemiological and laboratory investigations of infectious diseases of public health importance. This work is funded by and done on behalf of the Department of Health so that appropriate action can be taken to protect the public’s health. Ongoing and up-to-date information on the outbreak is made publically available through the weekly Situational Reports placed on the NICD website (see In addition, the website contains other useful information relating to listeriosis case notification and reporting, clinical management, laboratory identification and guidance for management following exposure to foodstuffs thought to be contaminated with the bacteria, and decontamination procedures. Interested parties are also referred to the websites of other public health institutes for additional information, notably the Centers for Disease Control in the USA (


The NICD will continue to report on laboratory-confirmed cases of listeriosis and will carefully monitor trends in case detection as numbers of cases are expected to decline over several months. This is due in part to the long incubation period of listeriosis (between consuming the contaminated food and developing illness) which is typically a few weeks but can be as long as 70 days; it is likely that some people who consumed the contaminated foods prior to the recall may still develop disease within the next two months. Additionally, there may be contaminated foods that have not been removed from vendors or homes despite the recall; given the long shelf-life of these products, this will also pose a risk for several months. Ongoing testing of food and food production environments as part of a Listeria surveillance program will also be done until the outbreak is over.


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