Homemade savory jelly caused an outbreak of foodborne botulism in Denmark last month, according to the Statens Serum Institut (SSI).

The agency, which is under the Danish Ministry of Health, said nine people became ill after eating dinner at a private party in Sønderborg. Danish authorities previously said a sample from the homemade dish was positive with botulinum toxin type A. The same type was identified in the patients.

Experts from Fødevarestyrelsen (Danish Veterinary and Food Administration), SSI and DTU Food – The National Food Institute found the outbreak was limited to those who ate dinner together. Foodborne botulism is extremely rare in Denmark. From1985 to 2017, SSI registered only six cases.

Homemade canned, preserved or fermented foods are often found to be the causes of foodborne botulism. Commercially processed food is another common cause.

Steen Ethelberg from SSI told Food Safety News that seven of the patients were lab confirmed and they developed varying degrees of symptoms in the following days. He added all were hospitalized. Most have now recovered.

Authorities confirmed botulinum toxin type A in a mouse assay after collecting and combining leftover food from the party and a glass that it was prepared in. However, they could not explain exactly how the savory jelly became contaminated or what ingredient was to blame.

Clostridium botulinum is a bacterium that produces botulinum toxins. The toxins block nerve functions and can lead to respiratory and muscular paralysis. Symptoms are caused by the toxin produced by the bacterium. They usually appear within 12 to 36 hours — with a range of four hours to 8 days — after exposure.

Homemade canned, preserved or fermented foods are common causes of foodborne botulism. Commercially processed food is another common cause.

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