Honey is the only known dietary reservoir of C. botulinum spores linked to infant botulism. For this reason honey should not be fed to infants less than one year of age. Due to the success of this public health message, fewer than 5% of recent infant botulism cases have been exposed to honey. The remaining 95% of infant botulism cases are thought to have acquired the spores from the natural environment. Clostridium botulinum is a ubiquitous soil-dwelling bacterium, and is found in soils throughout the US. Many infant botulism patients have been demonstrated to live near a construction site or an area of soil disturbance.
Infant botulism was first recognized in 1976, and is the most common form of botulism in the United States. There are 80 - 100 diagnosed cases of infant botulism in the United States each year. Infants are susceptible to infant botulism in the first year of life, with more than 90% of cases occurring in infants younger than six months.[2] Infant botulism results from the ingestion of the C. botulinum spores, and subsequent colonization of the small intestine. The infant gut may be colonized when the composition of the intestinal microflora (normal flora) is insufficient to competitively inhibit the growth of C. botulinum. Medical science does not yet completely understand all factors that make an infant susceptible to C. botulinum colonization. The growth of the spores releases botulinum toxin, which is then absorbed into the bloodstream and taken throughout the body, causing paralysis by blocking the release of acetylcholine at the neuromuscular junction. Typical symptoms of infant botulism include constipation, lethargy, weakness, difficulty feeding and an altered cry, often progressing to a complete descending flaccid paralysis. Although constipation is usually the first symptom of infant botulism, it is commonly overlooked.