RIVM has identified a cluster of 20 patients diagnosed with listeria over the past 2 years who are most likely to have been infected with an identical strain. This strain has been found in a meat slicing factory. Among them, three patients have died and one woman has had a miscarriage. The meat factory has issued a safety warning on 4 October and an immediate recall of the concerned products.
Source tracing
The source of the infection has been traced through cooperation between RIVM and the Netherlands Food and Consumer Product Safety Authority, NVWA. The strains found in the patients with a listeria infection were examined by a new technique that characterises the whole genome (Whole genome sequencing). An identical strain was found by RIVM in several patients and contacted the NVWA to compare the strain with strains from from food and factory sampling. After identification of a match , the NVWA undertook a follow-up research. To date, it is almost certain that the source for this cluster has been identified. The comparison of DNA profiles is a new research method, which enables linking sources with infected patients.
Listeria
Listeria bacteria are found in food, especially in raw foods and products that have been stored in the fridge for a long time, but also in the soil and in surface water. Listeriosis is a very rare disease. The risk of becoming ill is very low . In the Netherlands, 4 out of every million people are infected with listeria every year. Healthy people usually do not get ill, or only have mild complaints, similar to flu or stomach flu. The disease can be more serious in very young children, the elderly and people with weakened immune systems. Sometimes the disease is fatal. The infection in pregnant women may lead to a miscarriage, premature birth or serious illness of the child if it is infected during birth. About 80 cases of listeria infections are reported to RIVM every year.
People who have consumed potentially contaminated products are advised to contact their General Practitioner (GP) only in case they develop serious illness, accompanied by a high fever. The GP may decide to carry out additional diagnostic investigation . This also applies for pregnant women who have eaten potentially contaminated products. If infection with the listeria bacteria is diagnosed, treatment with antibiotics is started. There is no prophylactic treatment.