Botulism and Honey


On 2 June 2010 , the Food Standards Agency of the United Kingdom (UK) issued a press release for reminding parents not to feed honey to babies who are under a year old. This follows a case of rare but serious illness, called infant botulism.


Botulism is caused by a neurotoxin (destroyed if heated at 80 °C for 10 minutes or longer) produced by the bacterium Clostridium botulinum , which is anaerobic, gram-positive, spore-forming rod that commonly found in the soil. Although the toxin is destroyed by boiling for 10 minutes or longer; inactivation of spores requires much higher temperature. Three forms of botulism namely, food-borne, wound and intestinal (infant and adult) botulism are recognised, which differs in the site of neurotoxin production. The intestinal botulism was previously known as infant botulism.

Foodborne Botulism

  1. Human cases are often linked to the consumption of home-canned foods. Clostridium botulinum needs no oxygen to multiply . Canned, bottled or vacuum-packed foods, which are improperly processed, or only lightly processed and then stored in air tight containers at room temperature, will provide suitable environment for the bacterium to grow and produce toxin in these products. In addition, some strains of Clostridium botulinum can grow at refrigeration temperature; and foodborne botulism cases associated with refrigerated food stored in vacuum packaging or modified atmosphere packaging have been reported.
  2. Most foodborne botulism cases are caused by the ingestion of pre-formed toxin that is already present in food which was consumed without further cooking or reheating. Symptoms of foodborne botulism include marked fatigue, weakness, and vertigo often followed by blurred vision, dry mouth and difficulty in swallowing and speaking. Vomiting, diarrhoea or constipation may also occur. The toxin may also paralyse the breathing muscles and cause death if breathing assistance is not provided.

Infant botulism

  1. Infant botulism, first recognised in 1976, is caused by the ingestion of the Clostridium botulinum spores that germinate and grow in the intestine of infants and release toxin.
  2. Honey, which may be contaminated with the spores, is implicated in some cases. It is not known how honey becomes contaminated with Clostridium Botulinum. Spores of Clostridium Botulinum, which are commonly found in environment, may be picked up by bees and brought to the hive.
  3. Infant botulism rarely happens to persons over one year old as the better developed natural microbiological flora in their intestines do not favour the germination of the spores. Early symptom of infant botulism is constipation, followed by lethargy, difficulties in feeding, generalised muscle weakness and weak cry.  While most cases require hospitalisation, fatal cases are rare.

Local Case

Botulism was added to the list of statutory notifiable diseases in Hong Kong since 14 July 2008. There had been no confirmed case of botulism reported to Department of Health since it became a statutory notifiable disease.

Advice to the Trade

  1. ensure food products are properly processed to ensure safety, such as by following strict thermal processes, attaining appropriate pH values in the final products, and prudent use of preservatives.
  2. handle food products appropriately during transportation and storage to prevent the growth of the bacteria and the formation of toxin.

Advice to the Consumers

  1. Avoid feeding honey to infants less than one year old.
  2. Honey should not be added to baby food or used on a soother to quiet a fussy or colicky baby.
  3. For those individuals who do home-canning, follow proper canning requirements and hygienic procedures
  4. Boil home-canned food for at least ten minutes before eating as botulism toxin can be destroyed by high temperatures.
  5. Follow the handling and storage instructions given by manufacturers of canned, bottled and vacuum packed foods.
  6. Avoid consumption of food from containers (e.g. canned food) that appear to be damaged, bulged or spoilt.

Risk Assessment Section
Centre for Food Safety
July 2010