Health secretary Matt Hancock has ordered a “root and branch” review of NHS food after two more patient deaths were linked last week to a listeria outbreak. The new deaths bring the number of suspected fatalities to five and doctors have warned that further cases could occur.
Hancock said he was “incredibly concerned” after it emerged the patients were suspected of dying as a result of eating pre-packaged sandwiches and salads linked by the same supplier, The Good Food Chain.
The affected products have since been withdrawn from hospitals and Public Health England said evidence suggested all the deaths had occurred before the items were removed from circulation on 25 May.
“We need a radical new approach to the food that is served in our NHS,” added Hancock. “Our NHS should be at the forefront of supporting people to make healthy choices.”
A Public Health England official said investigations into the outbreak were taking place and were being conducted in partnership with the Food Standards Agency. Listeria is caused by the bacterium Listeria monocytogenes and can trigger very severe disease in humans. It usually affects people whose immune systems have been weakened – such as the elderly, pregnant women or patients taking immuno-suppressant drugs. The disease is caught by eating contaminated food.
The first three deaths were at Manchester University NHS foundation trust and Aintree University Hospital NHS foundation trust in Liverpool. One of the two new cases is understood to have died after these three cases. However, the other patient died before the three succumbed. Doctors have only just discovered the death was linked to the same strain of the bacterium.
“These two cases had already been reported to Public Health England but were re-analysed using whole genome sequence data,” said Dr Catherine Rees, associate professor in microbiology at Nottingham University. “This showed that the listeria isolated from these patients were highly likely to have come from the same source.”
The trusts where the latest two victims were receiving treatment have not yet been named, although PHE said there are now seven trusts across the country dealing with listeria cases. The first case showed symptoms on 25 April and sandwiches and salads were withdrawn on 25 May. It is understood that some of the products were sold at hospitals, while others were given to patients.
“Pre-packed sandwiches are recurrently incriminated in the UK in listeriosis episodes,” added Professor Jose Vazquez-Boland of Edinburgh University. “For example, in 2017 there was an outbreak in Yorkshire and the Humber that also involved sandwiches supplied to hospitals. There is clearly a warning here that microbiological controls for listeria need to be stepped up with pre-packed sandwiches.
“In general, foods involved in listeria infections are industrially processed foods that are kept at refrigeration temperatures and are consumed without previous cooking.”
The Good Food Chain, which supplied 43 NHS trusts across the UK, voluntarily ceased production. The company was supplied with meats from North Country Cooked Meat. Some of these have since tested positive for the outbreak strain of Listeria monocytogenes and the company has also stopped production. “Since the source has been traced, there should be no more exposure, but the bacterium’s long incubation period means that the risk of new cases coming to light cannot be ruled out yet,” added Rees.
In a statement, The Good Food Chain said: “The underlying cause of it [the outbreak] remains unclear. We understand the investigations being carried out are complicated, but we hope the authorities will pursue their inquiries with all urgency so the wider industry can learn any lessons as soon as possible.”
The lunchbox killer
Listeria monocytogenes is probably the deadliest bacterial foodborne pathogen in the western world, and while it mainly affects individuals such as the elderly, pregnant women, infants, and those taking immuno-suppressant drugs, it can also affect other people. It is also one of three foodborne pathogens that put the highest burden on healthcare facilities. There are around 200 cases of listeriosis per year in England and Wales and about 30 deaths. However, that fatality rate can reach higher levels in some groups, such as pregnant women.
Listeriosis is a problem because it is present in the environment and can easily contaminate pre-packed foods. Furthermore, in many cases it does not occur as a normal foodborne illness that is associated with diarrhoea and vomiting but as an infection of the foetus or as meningitis. Survivors can be left with permanent damage, such as brain damage.
Despite the major advances in food safety, Listeria monocytogenes still finds its way into foods. Our protection relies heavily on having a well-monitored system of food production and distribution combined with a good centralised surveillance process that can raise the alarm when cases appear. Then the disease can be linked to specific foods. As we have seen with this outbreak, good surveillance was key to identifying cases. The food responsible (sandwiches) was pinpointed and the contaminated ingredient (meat) was identified, leading to the immediate removal of the product.
However, the disease’s long incubation period – up to 70 days – often makes it difficult to identify the guilty food product. In this outbreak, there were cases where authorities could not originally identify the source. However, once they discovered the outbreak they were able to link new cases with the outbreak.
It is clear that, without good surveillance, authorities would have been unaware of the outbreak for a very long time. This was the case with last year’s listeriosis outbreak in South Africa that had been occurring for more than a year and had killed 216 people before it was pinpointed.
Clearly the public should not be worried this time as the contaminated products have been removed. Some cases may still appear due to the disease’s long incubation period, but this should not be a cause of concern for the public. The decision to review food sold in hospitals is a sound step, nevertheless, as patients and pregnant women remain at risk.
Dr Kimon Andreas Karatzas, Reading University