Ready-to-eat chicken, including wraps and sandwiches, are thought to be behind a long-running salmonella outbreak sweeping the UK and Europe.
In the UK, 81 people have been infected with the bacteria and one has died, according to the European Centre for Disease Prevention and Control (ECDC).
Only Finland has recorded more cases – 89 in total – with five people having been hospitalised with sepsis.
The cases are part of a wider outbreak in which 196 infections have been identified in multiple countries across Europe since September last year – yet experts remain unsure of the source of the bacteria.
The ECDC said multiple food distribution chains have been implicated, adding that new cases are “likely to occur” until the original source has been identified and controlled.
Professor Hugh Pennington, a microbiologist who has investigated multiple food poisoning outbreaks on behalf of the UK government, described the outbreak as a “mystery” and said there was “no obvious common source”.
Salmonella bacteria are found in the stomachs of poultry and livestock. Birds and animals can be infected through feed, in hatcheries or through faeces on the way to abattoirs, where slaughter and processing can also spread the infection.
There are more than 2,000 types of salmonella, the most virulent of which can be life-threatening, particularly for infants and elderly people.
Patients typically suffer from diarrhoea, fever and stomach cramps. In the most severe cases, sepsis and kidney failure can occur.
The strain of salmonella spreading throughout Europe, including France, Germany, Ireland and the Netherlands, is Mbandaka ST413, which has hospitalised a total of 19 people to date.
“Based on available information from case interviews and trace back investigations, the working hypothesis is ready-to-eat chicken products containing contaminated chicken meat as likely vehicles of infections, with freshly sold chicken as another possible vehicle,” the ECDC said.
In the UK, 18 out of 26 analysed cases (69.2 per cent) had eaten ready-to-eat chicken products within the week prior to the onset of symptoms, the ECDC said.
“Most notably, chicken products such as slices/pieces used in sandwiches and wraps were reported at a higher than expected rate compared to national dietary survey data.”
A further 38.5 per cent of the cases “indicated purchase of chicken products from local cafes and restaurants, including wraps, sandwiches/baguettes and kebabs,” the report said.
Similar trends have been reported in Finland, which, as of 8 November, had recorded the highest number of salmonella infections from the current outbreak.
Fifteen cases in Finland reported consumption of six ready-to-eat chicken products, including wraps and sandwiches, from three brands. All 15 cases had consumed at least one ready-to-eat chicken product.
Two products were marketed under the same brand name and traced back to an Estonian company. However, investigators were unable to establish the firm as the source of infection.
Prof Pennington said that chicken feed could be a potential source of Salmonella Mbandaka ST413.
He explained that ready-to-eat chicken products “should have no live salmonella in them,” having been treated and cooked.
“An infective dose of Salmonella is usually high, so for it to be present in ready-to-eat products in amounts capable of causing an infection suggests something wrong in their production,” Prof Pennington added.
A separate outbreak of salmonella was reported earlier in the year by the UK Health Security Agency, which traced the infection to chocolate products made at a factory in Belgium.
In the late 1980s, the government was criticised for its handling of a salmonella outbreak after then health minister Edwina Currie wrongly claimed that “most of the egg production in this country, sadly, is now affected with salmonella”.
Her comments resulted in the destruction of around 400 million eggs and the slaughter of around 4 million hens.
Protect yourself and your family by learning more about Global Health Security