No outbreak of listeriosis


The National Institute for Communicable Diseases has issued a statement saying that there is no evidence of an outbreak of listeriosis.

According to the institute, the number of cases reported since the official end of the 2017/2018 listeriosis outbreak is well within (and in fact, below) the expected range for sporadic disease.

Furthermore, there have been no unusual trends in the epidemiological patterns of disease, or in the whole genome sequencing analysis of isolates from patients; such data are analysed on an ongoing basis in order to detect possible clusters or outbreaks.

Listeria monocytogenes is ubiquitous in the environment, so it is likely that accidental contamination of food occurs fairly frequently, and that consumption of contaminated food may lead to listeriosis, particularly in vulnerable people at high risk for disease.

For the 12 months following the official end of the 2017/2018 outbreak (3 September 2018 – 18 September 2019), a total of 87 laboratory-confirmed listeriosis cases were reported. This is below the expected range. Outcome data is currently available for 77% (67/87) of cases, of which 31% (21/67) died. This is not unexpected, because listeriosis is a severe disease that targets vulnerable people at high risk and typically has a fatality rate of 20-30%.