UK infant botulism case traced to peanut butter

Researchers have described a confirmed case of infant botulism linked to peanut butter that occurred in the United Kingdom in May 2024.

A 6-month-old infant was hospitalized after being given peanut butter to reduce the risk of developing a peanut allergy. The child’s father had a severe peanut allergy, and the parents chose to introduce peanut butter from 6 months of age.

Clostridium botulinum type A was detected in the infant’s feces and the peanut butter. Whole genome sequencing confirmed identical strains, identifying the peanut butter as the source of infection. 

Scientists said that as more caregivers follow guidance to introduce nuts and seeds early in infants’ diets, more babies are likely to be exposed to spore-bearing foods, potentially posing a botulism risk.

Illness history
Nuts may become contaminated with Clostridium botulinum spores at source or during processing.

According to the study, published in the journal Eurosurveillance, Infant botulism is rare in the UK with only 23 confirmed cases since 1977.

A previously healthy infant presented with a 1-day history of progressive lethargy, poor feeding, hoarse cry and noisy breathing, following two weeks of constipation.

The infant was treated initially for suspected sepsis. By day five of illness, lethargy had not improved. After botulism was considered likely, Clostridium botulinum antitoxin was ordered from the United States. The infant required intubation and ventilation on day six because of worsening hypoventilation resulting in respiratory failure.

On day seven, feces were referred to the Clostridium botulinum reference laboratory at the UK Health Security Agency (UKHSA). Clostridium botulinum type A was detected by PCR the next day and then on culture, confirming the diagnosis of infant botulism.

Botulism risk from peanut introduction
Antitoxin was administered on day 10. The infant required non-invasive respiratory support until day 30. The patient was discharged on day 44. By day 65, muscular tone and power had normalized, but constipation persisted. By day 110, the infant had developed severe constipation. This improved by day 140 and resolved by day 234.

The infant’s food history revealed they had been fed incremental doses of a commercial peanut butter, starting 10 days before onset of symptoms. The used container was tested at the reference lab, and Clostridium botulinum type A was detected.

The product was made of roasted peanuts without added honey. Raw peanuts harbor environmental spores which are heat resistant and can contaminate the peanut butter during processing.

“We did not test the peanut butter for botulism neurotoxin (BoNT). However, we would not expect it to have been present as the slow progression of symptoms was clinically consistent with sporulation and toxin production in the infant’s intestinal tract rather than preformed toxin causing food botulism. There were no other reported cases of food botulism notified in England at the time,” said scientists.

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