Two major foodborne outbreaks have recently been highlighted at a European conference on infectious diseases.

Presentations at the European Scientific Conference on Applied Infectious Disease Epidemiology (ESCAIDE) covered an E. coli outbreak from Nestlé pizzas in France and a multi-country monophasic Salmonella Typhimurium outbreak due to Ferrero chocolate.

In February 2022, Santé Publique France identified more cases of the pediatric hemolytic uremic syndrome (HUS) than usual with eight infections. Cases were positive for Shiga toxin-producing E. coli (STEC) O26:H11 or O103:H2 identified by whole genome sequencing (WGS). only two people were sick from E. coli O103.

Products and flour positive for E. coli
Overall, 56 confirmed and two probable cases were found nationwide with onset between Jan. 18 and April with a median age of 6. There were 50 cases of HUS, two children died and two others had severe aftereffects of infections.

A patient-control study revealed a strong association between consumption of the pizza and disease.

In total, 35 of 40 cases reported eating Buitoni Fraîch’Up frozen pizza and 35 of 37 cases with pizza purchases on loyalty cards bought this brand.

STEC O26:H11 and O103:H2 outbreak strains were isolated from pizzas sampled in patients’ homes and at the manufacturing plant. E. coli was also isolated in the flour used to make pizzas.

Frozen pizzas were made in one factory in Caudry, with an individual production line and no re-baking of dough before the sale. Nestlé is looking to resume operations but approval from French authorities is pending.

Investigations confirmed frozen pizzas as the source of the largest E. coli-HUS outbreak ever documented in France. In March, Nestlé recalled and withdrew the incriminated pizzas, and production at the plant was suspended. A criminal inquiry into the incident was opened in May.

Typical baking temperatures and times for frozen pizzas should eliminate infection risk. Investigations are ongoing to understand the origin of contamination and persistence of STEC in baked pizzas. A scientific review is planned to assess E. coli risk in flour in France and management in foods made from flour, according to the presentation.

Salmonella chocolate outbreak
ESCAIDE, from Nov. 23 to 25, was held in Stockholm and remotely. It was organized by the European Centre for Disease Prevention and Control (ECDC).

Three research posters were about the monophasic Salmonella Typhimurium outbreak from Kinder chocolate made by Ferrero in Belgium that sickened more than 450 people. They covered national responses in the United Kingdom, Belgium, and Ireland.

In February 2022, the UK reported a cluster of Salmonella Typhimurium infections. By early April, 150 cases, predominantly in females and children, were seen in the EU and UK with sample dates from late December 2021 to the end of March 2022. The UK issued an EpiPulse alert in mid-February and the first contact between UK and Belgian food safety authorities was on April 1.

Initial UK patient interviews suggested Kinder eggs were the likely vehicle of infection or processed chicken. A case-control study included 26 cases and 106 controls aged under 11. It provided strong evidence that Kinder eggs were a vehicle for the outbreak and supported the recall of Ferrero products in April based on descriptive epidemiology and food chain investigations.

Other products showed a significant association in the model but this was not of the same magnitude as chocolate eggs and without further supporting evidence from other investigations, they can’t be considered as key vehicles for UK cases, said scientists.

Two clusters
In Belgium, microbiological investigations found two clusters. Researchers identified 62 probable cases with 39 in cluster 1 and 23 in cluster 2.

They had illness onset from mid-January until April this year and a peak was seen in mid-February. Of the 62 patients, 54 were 1 to 9 years old. Among 44 interviewed patients, 19 were hospitalized and 41 consumed products from the factory, and 35 reported eating Kinder Surprise.

Seven of 229 food products tested positive for Salmonella; whole genome sequencing analysis indicated matches with both clusters. In December 2021, Salmonella was found in samples during a self-check in the factory, these isolates matched with the later identified clusters.

Eleven types of products were recalled and food safety authorities shut the factory in Arlon in April but it reopened in June. An investigation into the incident by the Luxembourg Public Prosecutor’s Office is ongoing.

Following the EpiPulse alert in mid-February, an investigation started in Ireland one month later after identifying seven cases with a sequence identical to the strain responsible for the international outbreak.

Two distinct strains caused 16 illnesses but one of the strains only led to one illness in Ireland. Most of those sick were female and under 10 years old but the age range was from 1 to 56. Four people were hospitalized. People fell sick from late January to the end of March.

A matched case-control study was used to confirm the source of infection. Nine cases and 24 matched controls were included. The odds of having consumed a specific Kinder product were seven times higher in cases notified as monophasic Salmonella Typhimurium versus cases of other gastrointestinal diseases. This product was consumed in seven of nine cases. The odds of having any of the recalled products were 10 times higher in monophasic Salmonella Typhimurium cases versus cases of other gastrointestinal diseases.