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.

The role of breast-feeding and formula-feeding as factors possibly predisposing to the development of illness remains unsettled. All studies to date have identified an association between being breast-fed and being hospitalized for infant botulism 2, 4, 15, 16, 19, 23, 25. This finding has resulted in one perspective that holds that breast-feeding predisposes to the development of illness 15, 16, 23, whereas the other perspective holds that breast-feeding slows its onset sufficiently to permit hospitalization to occur 1, 2, 3, 4. However, among hospitalized patients, the mean age at onset of infant botulism in formula-fed infants (7.6 weeks) was significantly younger and approximately half that of breast-fed infants (13.8 weeks). In addition, the fulminant-onset infant botulism patients who stopped breathing and died at home all were formula-fed. The relative susceptibility of formula-fed and breast-fed infants to the acquisition of infant botulism and the resultant severity of their disease may reflect differences in the availability of suitable ecologic niches in the intestinal flora for C. botulinum, differences in the availability of immune factors (such as lactoferrin and secretory IgA) contained in human milk but not in formula milk,9 or other differences not identified yet.

Honey is the one dietary reservoir of C. botulinum spores thus far definitely linked to infant botulism by both laboratory and epidemiologic evidence.5, 6, 7, 10, 11, 13, 18, 22, 24 To date, 35 instances worldwide are known in which C. botulinum spores have been found in the actual honey fed to an affected infant before the onset of illness. In each instance, the toxin type (A or B) of the spores in the honey matched the toxin type (A or B) of the C. botulinum that caused the infant's illness; the probability that such perfect concordance occurred by chance is less than 1 in 10 billion. C. botulinum spores have been found in the honey from the United States, Argentina, Australia, Canada, China (Taiwan also), Denmark, Finland, Italy, Norway, Spain, Japan, and Central America,6, 7, 10, 11, 13, 17, 18, 20, 22, 24 but not in honey from the United Kingdom.8 For these reasons and because honey is not nutritionally essential, all major pediatric, public health, and honey industry agencies in the United States have joined in the recommendation that honey not be fed to infants. In 2000, several honey brands sold in the United States began to carry a warning to not feed honey to infants; an equivalent label first appeared on British honey in 1996.

Discussion of the possible role of corn syrup in infant botulism is necessitated by two reports. In 1982, the U.S. Food and Drug Administration (FDA) found C. botulinum type B spores in approximately 0.5 percent (5 of 961) of previously unopened retail samples of light and dark corn syrup 13; the manufacturer then made changes in the production process. In 1989, the CDC reported a 2-year epidemiologic study of U.S. cases from all states except California.23 By subgrouping patients by age and using logistic regression modeling techniques, researchers were able to obtain a statistical association between the triad of corn syrup exposure, breast-feeding, and an age of 2 months or older at onset.21, 23

In contrast to these reports, a 1988 Canadian survey found no C. botulinum spores in 43 corn syrup samples.10 A 1991 FDA market survey of 738 syrup samples (354 of which were light corn syrup and 271 were dark corn syrup) concluded that none contained C. botulinum spores 14. In addition, a 1979 epidemiologic study that simply compared corn syrup exposure rates in 41 cases and 107 control infants identified feeding of corn syrup as a significant protective factor against the acquisition of type A infant botulism.6 The explanation offered for the latter observation was that if a parent chose corn syrup as a sweetener for the infant, honey was unlikely to have been fed to the child as a second sweetener. Thus, on the basis of evidence presently available, corn syrup does not appear to be a source of C. botulinum spores or a risk factor for the acquisition of infant botulism.

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 probably was acquired by swallowing spores adherent to airborne microscopic (invisible) dust.

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