Botulinum Toxin Blocks Neurotransmitter Release
Scientists have identified 7 distinct botulinum toxins – A through G – which are produced by different strains of C. botulinum or closely related bacteria. Bacteria capable of producing toxin types A and B are found in honey. Once a botulinum toxin enters your bloodstream, it attaches to receptors on your nerve cells and permanently blocks the release of acetylcholine, a neurotransmitter that is necessary for muscle function. The ensuing paralysis, if untreated, leads to respiratory arrest and death. With lethal doses in the sub-1mcg range, botulinum toxins are among the most potent poisons known.
An April 2002 review in “American Family Physician” reported that approximately 250 cases of infant botulism are diagnosed in the U.S. each year, the majority of them occurring in Utah, Pennsylvania and California. Less than 2 percent of these infants die from their illness, but recovery can be prolonged. Although honey ingestion is a primary risk factor for infant botulism, only about 20 percent of cases report a history of honey consumption.
Infant botulism can be difficult to recognize. The first sign of infant botulism is usually constipation, which can last for several weeks before other signs – weakness, poor feeding or suckling ability, loss of head control, weak cry, poor eye movement, drooping eyelids and breathing difficulties – appear. Specialized tests can usually detect C. botulinum and its toxin in the stool of an afflicted child. Once it is diagnosed, infant botulism is treated with a specific type of intravenous immune globulin. Mechanical ventilation (artificial respiration), tube feeding and physical therapy are usually required. On average, infants remain hospitalized for 6 to 7 weeks.
Adults usually develop botulism following consumption of food containing preformed botulinum toxin. Improperly canned foods are the most common source of preformed toxin. Recently, several instances of botulism have been linked to consumption of pruno, or “prison wine.” Rarely, adult botulism results from wounds contaminated by C. botulinum. Increasingly, a form of adult intestinal colonization botulism, which is similar to infantile botulism, is being reported in the medical literature. This form of botulism occurs in people with altered intestinal anatomy or physiology, such as patients with colitis or those who have undergone intestinal bypass procedures. Since intestinal colonization botulism stems from ingestion of C. botulinum spores, susceptible individuals could fall ill following consumption of contaminated honey. Adult botulism is treated similarly to infant botulism.
Infants younger than 1 year are believed to be more susceptible to spore-caused botulism because they don’t possess a full complement of intestinal bacteria to prevent C. botulinum from multiplying. These children should not be fed honey. In homes where honey is frequently used by older family members, environmental surfaces and utensils within a baby’s reach should be cleaned regularly to prevent ingestion of spores. Adults with chronic intestinal diseases or who have undergone bypass procedures may want to avoid honey. Home canners should scrupulously follow food preservation guidelines, and home-canned foods should be thoroughly inspected and cooked after opening.
1. N Cox, R Hinkle. Infant Botulism. American Family Physician. 2002;65(7):1388-1393
2. Medscape.com: CBRNE – Botulism
3. SS Arnon, et al. Human botulism immune globulin for the treatment of infant botulism. New England Journal of Medicine. 2006;354:462-471