Infant botulism: advice on avoiding feeding honey to babies and other possible risk factors.
Botulism is a serious, paralytic illness caused by the action of neurotoxins, usually produced by Clostridium botulinum. These toxins block the release of the neurotransmitter acetylcholine at the neuromuscular junction, preventing muscle contraction and resulting in a characteristic floppy paralysis.
Human botulism is best known as a food-borne disease, caused by ingestion of preformed neurotoxin in foods where C. botulinum has grown. Fortunately, it is very rare in the UK. However, botulism can also be transmitted by other routes. 'Wound' botulism arises when C. botulinum causes a local soft tissue infection and produces neurotoxin in the wound. In the UK this has been exclusive to people who inject drugs. Botulism can also occur after accidental exposure to botulinum neurotoxin when it is used in a therapeutic or cosmetic product (NHS, 2013a). Finally, there is infant botulism, which results from neurotoxin produced by C. botulinum during intestinal colonisation. This final manifestation of the disease is the subject of this article: infant botulism is now the most common presentation of this disease in the UK.
Infant botulism is a rare disease. A total of 16 cases have been detected in the UK over the past 35 years and eight of these occurred between 2009 and March 2013. It is a serious illness, generally affecting infants under the age of one year (usually under six months) and its management can require prolonged paediatric intensive care.
C. botulinum is found in the environment surviving for long periods in soil, dust and mud, in a dormant spore form. As a consequence it can occur naturally in foods and food materials. In general, this is not a health problem as foods usually do not provide the right conditions for C. botulinum spores to germinate and produce toxin. Any spores that do get into the human gut are outcompeted by the normal bacterial gut flora of older infants, children and adults, which is why they do not tend to be affected. However, the gut flora of infants less than one year of age is less well developed and not always able to outcompete growth of C. botulinum. If botulinum neurotoxin is produced in the infant gut it is transported to the neuromuscular junction, leading to flaccid muscle paralysis that in infants is known as floppy baby syndrome. Initial symptoms often include constipation, lethargy, poor feeding, weak cry, droopy eyelids, poor head control and progressive weakness. Infants may have difficulty breathing, leading to respiratory arrest and may require mechanical ventilation. Recovery from infant botulism can take several weeks or months as it depends on regeneration of the nerve endings. Fortunately, there is full recovery in most cases. Until recently, the only treatment for infant botulism was meticulous supportive care but, since 2005, a human-derived antitoxin for treatment of babies (BabyBIG) has been available from the USA, which, if given sufficiently early, has been shown to improve recovery and reduce the length of hospital stay.
Infants are often exposed to C. botulinum spores in the environment, but this alone is unlikely to be sufficient to cause illness. It is believed that some sort of disturbance of the infant gut flora occurs at the same time as exposure to spores, providing a window of opportunity for spores in the gut to grow and produce neurotoxin. Antibiotic treatment or changes in the infant diet, such as weaning or a change from breast to formula milk, have sometimes been associated with cases of infant botulism and may have disturbed the infant gut flora, enabling C. botulinum to grow (Arnon, 2004). In the majority of cases the source of spores is unknown--but some risk factors have been identified and are discussed below.
Honey and corn syrup have been shown to contain C. botulinum spores and both foods are recognised as potential sources of the organism, particularly in the USA where this disease is much more commonly recognised (Koepke et al, 2008; Anion, 2004; NHS, 2013a). Honey, in particular, has been implicated as a source of C. botulinum spores as, in some cases where honey was given before onset of illness, spores of the same C. botulinum toxin type as detected in the infant were also found in left over honey from the infant's home. Six out of eight of the most recent infant botulism cases in the UK have had a history of being given honey; and for two of the cases C. botulinum of the same toxin type was detected in honey as recovered from the affected infants. For the other four cases, this was not confirmed (Koepke et al, 2008).
The current health advice is that honey should not be given to babies under one year of age (Advisory Committee on the Microbiological Safety of Food (ACMSF), 2006; NHS, 2013b); but it is clear from recent cases in the UK that this advice is not always followed by parents and carers of infants (Koepke et al, 2008). In addition, advice from the ACMSF states that infants under 12 months old should not be given foods that contain honey, unless they have received a full botulinum cook (ie, 121oC for three minutes or an equivalent process control (ACMSF, 2006)).
Honey may be given to infants for a variety of reasons; for example, to soothe restlessness or to sweeten other foods, while in some cultures it may be customary to give honey to newborn babies. Members of the British Honey Importers and Packers Association (BHIPA) have a voluntary code of practice of product labelling and since 1996 honey on sale in the UK has carried a warning that it should not be given to infants under 12 months of age (Food Standards Agency (FSA), 2007). The FSA recommends that any other packers and suppliers of honey should follow this precautionary labelling approach (FSA, 2007). However, it is a voluntary code and is not applied to all products containing honey, including imported products.
In addition, the FSA advice does not cover legibility and the warning on jars of honey is often small and not always clearly visible and thus may not be understood. Studies have shown that many parents and carers are unaware of the risk of infant botulism and feeding honey to infants (Fenicia et al, 2007; Kumar et al, 2011). While very few infants who consume honey develop botulism, this is a rare but serious disease which can be difficult to recognise, even by highly specialised medical professionals. It is not clear how often less serious forms of the disease occur and, although not all cases of infant botulism are associated with honey consumption, honey is the most common food that has been identified as a risk factor. Due to the recent increase in reported cases of infant botulism in the UK, as well as the severity of symptoms and length of recovery, it is important that advice is reiterated to parents and other carers not to feed honey to infants less than 12 months old (NHS, 2013b).
Additional possible risk factors
C. botulinum spores may be ingested through contact with the environment and soil or dust disturbance close to the infant's home. Construction work, a farm or windy conditions have been highlighted as risk factors in the USA where infant botulism is more frequently reported (Fenicia and Anniballi et al, 2009; Arnon, 2004).
C. botulinum spores have also been found in certain medicinal plants used to make teas or infusions; for example, chamomile (Bianco et al, 2008). In Argentina and other Mediterranean countries, including Italy, Spain and Greece, such teas are commonly given to infants either as a remedy for colic or just as a beverage. Boiling water would not destroy the spores as they are resistant to heat and if swallowed by infants they could germinate, grow and produce botulinum toxin in the infant gut. Cases of infant botulism have been associated with consumption of chamomile tea in some of these countries so such drinks should also be considered a possible risk factor for infant botulism (Fenicia and Anniballi, 2009).
In 2011 the first case of infant botulism was reported in the Republic of Ireland and this was found to be caused by a rare strain of Clostridium butyricum, a species related to C. botulinum that can occasionally produce botulinum neurotoxin (HPA, 2013). Samples taken from the infant's home showed a link with terrapins kept as pets by the family, as the same neurotoxin-producing strain isolated from the infant was also found to be present in terrapin tank water and sediment.
Eight months before this case, there was an infant botulism case in England, which was also caused by a neurotoxin-producing strain of C. butyricum. At the time of illness this case was thought to be linked to honey consumption, although C. butyricum was not detected in leftover honey (HPA, 2010). Subsequent investigations, however, revealed that terrapins were also kept as family pets at the time this infant became ill. Although terrapins as a source of spores for infant botulism is likely to be rare, these new findings reinforce the need for advice for parents and other carers of young children about the microbiological risks of reptiles, including terrapins, as pets in households where there are babies, children under the age of five, the elderly and those with weakened immune systems (HPA, 2009). Reptiles are known to carry a range of pathogens, including Salmonella and these can lead to human illness, which may be severe in infants and young children.
Potential exposure to young infants from the C. botulinum spores in the environment cannot be eliminated and it should be emphasised that infant botulism is an extremely rare disease. However, it would be prudent to follow the advice from the Infant Botulism Treatment and Prevention Program (www.infantbotulism. org), which states: 'It deserves emphasis that for most cases of infant botulism, no source of C. botulinum spores is ever identified, even circumstantially. In these cases, the illness was probably acquired by swallowing spores adherent to airborne microscopic (invisible) dust. The only known prevention measure for infant botulism is to avoid feeding honey to infants 12 months of age or less. Breastfeeding may slow the onset of illness if it develops.'
In summary, honey is a known dietary risk factor for infant botulism and six of the eight most recent reported cases of infant botulism in the UK have had a history of honey consumption. It is important that parents and carers are provided with, and understand, advice that honey should not be fed to infants under 12 months of age.
Two recent cases of infant botulism in the UK and Ireland, caused by a rare strain of C. butyricum producing BoNT, are likely to have acquired their infection from pet terrapins. This highlights a continued need for advice to parents and other carers of infectious risks from reptiles, including terrapins, and reinforces the statement that all reptiles should all be presumed to carry pathogens (eg, Salmonella) in their gut and suitable precautions should be taken to prevent infections (HPA, 2009).
Infant botulism is a very rare disease; however, due to its severity, the lengthy recovery and associated healthcare costs it is important that preventive advice to help reduce the risk of infection be provided to those with caring responsibilities for infants.
CPD questions (please visit www.communitypractitioner.com/CPD to submit your answers) 1. What the most common form of botulism in the UK? A. Foodborne botulism B. Infant botulism C. Wound botulism D. Iatrogenic botulism 2. Infant botulism results from the consumption of pre-formed toxin in food. True or false? A. True B. False 3. Which of these symptoms is not typically associated with infant botulism? A. Weak cry B. Constipation C. Fever D. Droopy eyelids 4. Which of these risk factors has not been associated with infant botulism? A. Dusty environment B. Eating canned food C. Drinking herbal tea D. Pets 5. Infant botulism most commonly occurs in infants: A. Shortly after delivery B. Under six months C. Up to one year D. From one to three years 6. BabyBIG is a treatment for infant botulism based on: A. Human-derived antitoxin B. Small doses of toxin C. Sheep-derived antitoxin D. A cocktail of antibiotics 7. Which of the following statements is false? Recovery from infant botulism usually ... A. Takes several weeks B. Is dependent on regeneration of the nerve endings C. Requires meticulous supportive care D. Results in permanent disability 8. Which of the following statements is false? Terrapins kept as pets: A. Are suitable for very young infants B. Are suitable for children under five C. Have been associated with infant botulism D. Can be a source of salmonellosis 9. What causes the clinical symptoms of infant botulism? A. Clostridium botulinum bacteria B. Clostridium botulinum neurotoxin C. Honey D. Botulinum spores 10. What measures can be taken to minimise the risk of infant botulism? A. Do not feed honey to infants under one year B. Give herbal teas to infants C. Keep your infant indoors D. Wash hands between touching or feeding pets and handling infants
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Kathie A Grant
Public Health England, London
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|Title Annotation:||PRACTICE: CPD|
|Author:||Grant, Kathie A.; McLauchlin, Jim; Amar, Corinne|
|Date:||Jul 1, 2013|
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