HPR volume 17 issue 11: news (26 and 28 September 2023)
Updated 28 December 2023
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Outbreak of foodborne botulism in France affecting British nationals
At the beginning of September 2023, French public health authorities identified a cluster of cases of suspected food botulism in Bordeaux when the area was experiencing a high number of visits from tourists attending the men’s Rugby World Cup taking place across the country.
The UK Health Security Agency (UKHSA) was notified of the outbreak on 13 September as it involved a small number of British nationals.
The outbreak was rapidly traced by French authorities to home-prepared sardines in oil served at a Bordeaux restaurant. The implicated food was served to customers between 4 and 10 September 2023 and an estimated 29 people were identified as having been exposed. Contact was made with individuals across countries in Europe and North America and the French authorities issued a public warning on 13 September urging individuals who ate at the restaurant between 4 and 10 September to contact a healthcare professional. Symptoms experienced by exposed individuals ranged from no symptoms to more severe illness, with one death reported. The Reference Laboratory in France subsequently detected Clostridium botulinum neurotoxin type B in the sardines that were served at the restaurant.
Foodborne botulism is rare in the UK but is a very severe illness that is often fatal if not treated early. The condition is caused by ingestion of pre-formed neurotoxin produced by the bacterium Clostridium botulinum in food stored in airtight containers such as canned foods, homemade pickles or food preserved in oil. There have been only 8 microbiologically confirmed cases in the UK since 2010; previous cases in the UK have been associated with local and imported foods including tuna in oil, wild mushrooms, olive in brine and commercially prepared korma sauce. Most botulism cases seen in the UK over the past decade were not foodborne; they were in people who had injected contaminated heroin.
In foodborne botulism, vomiting and diarrhoea followed by constipation can precede neurological symptoms (which include blurred vision, difficulty swallowing, and rapidly progressive descending symmetrical paralysis). The illness is toxin mediated and there is usually no person-to-person transmission. The incubation period is generally between 12 and 36 hours but can be up to 8 days. Contact tracing of individual customers was facilitated by French authorities contacting various banks identified from credit card receipts used for payment at the restaurant.
UKHSA released a statement to the media on 13 September asking members of the public who ate at the Tchin Tchin Wine Bar in Bordeaux between 4 and 10 September to seek urgent medical care if they felt unwell. A national incident response including UKHSA and devolved administrations was initiated to co-ordinate communications and follow-up of exposed people and cases.
As a result of the French authorities’ contact tracing exercise, 3 UK residents who had eaten at the restaurant presented with gastrointestinal and neurological symptoms to their local healthcare settings on their return home. All 3 were treated with botulinum anti-toxin and were discharged after short hospital admissions. Three further UK nationals identified as exposed were contacted by UKHSA and had no symptoms.
The Reference Service for C. botulinum at UKHSA Colindale confirmed the clinical diagnosis of botulism in the 3 individuals that were hospitalised in England with the detection of C. botulinum type B from the stool samples 4 to 5 days after the date of consumption of sardines. Botulinum neurotoxin was not detected in a serum sample taken from one of these individuals. This negative result might be due to the late collection of the sample, 4 days after exposure.
As of 18 September, the maximum incubation period for botulism following the last exposure date had elapsed, meaning that no new cases are expected. The national incident response in the UK was stepped down on 19 September.
Infection reports
Acute hepatitis B: national enhanced surveillance report January to December 2020
Travel-associated infections in England, Wales and Northern Ireland: 2022