Botulism also known as botulinus intoxication is a rare but serious paralytic illness caused by botulinum toxin which is a protein produced under anaerobic conditions by the bacterium Clostridium botulinum, and affecting a wide range of mammals, birds and fish.
Symptoms
The classic symptoms of botulism include double vision, blurred vision, drooping eyelids, slurred speech, difficulty swallowing, dry mouth, and muscle weakness. Constipation may occur. The doctor's examination may reveal that the gag reflex and the deep tendon reflexes like the knee-jerk reflex are decreased or absent.
Infants with botulism appear lethargic, weak, and floppy, feed poorly, become constipated, and have a weak cry and poor muscle tone. In infants, constipation is often the first symptom to occur.
These are all symptoms of the muscle paralysis that is caused by the bacterial neurotoxin. If untreated, these symptoms may progress to cause paralysis in various parts of the body, often seen as a descending paralysis of the arms, legs, trunk, and breathing muscles.
Infant botulism
Infant botulism was first recognized in 1976, and is the most common form of botulism in the United States. There are 80 to 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. 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.
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. Many infant botulism patients have been demonstrated to live near a construction site or an area of soil disturbance.
Prevention
Although the botulinum toxin is destroyed by thorough cooking over the course of a few minutes, the spore itself is not killed by the temperatures reached with normal sea-level-pressure boiling, leaving it free to grow and again produce the toxin when conditions are right.
A recommended prevention measure for infant botulism is to avoid feeding honey to infants less than 12 months of age. In older children and adults the normal intestinal bacteria suppress development of C. botulinum.
While commercially canned goods are required to undergo a "botulinum cook" in a pressure cooker at 121 °C (250 °F) for 3 minutes, and so rarely cause botulism, there have been notable exceptions such as the 1978 Alaskan salmon outbreak and the 2007 Castleberry's Food Company outbreak. Foodborne botulism is the rarest form though, accounting for only around 15% of cases (US) and has more frequently been from home-canned foods with low acid content, such as carrot juice, asparagus, green beans, beets, and corn. However, outbreaks of botulism have resulted from more unusual sources. In July, 2002, fourteen Alaskans ate muktuk (whale meat) from a beached whale, and eight of them developed symptoms of botulism, two of them requiring mechanical ventilation. Other, but much rarer sources of infection (about every decade in the US) include garlic or herbs stored covered in oil without acidification, chilli peppers, improperly handled baked potatoes wrapped in aluminium foil, tomatoes, and home-canned or fermented fish. Persons who do home canning should follow strict hygienic procedures to reduce contamination of foods. Oils infused with fresh garlic or herbs should be acidified and refrigerated. Potatoes which have been baked while wrapped in aluminum foil should be kept hot until served or refrigerated. Because the botulism toxin is destroyed by high temperatures, home-canned foods are best boiled for 10 minutes before eating. Metal cans containing food in which bacteria, possibly botulinum, are growing may bulge outwards due to gas production from bacterial growth; such cans should be discarded. Any container of food which has been heat-treated and then assumed to be airtight which shows signs of not being so, e.g., metal cans with pinprick holes from rust or mechanical damage, should also be discarded. Contamination of a canned food solely with C. botulinum may not cause any visual defects (e.g. bulging). Only sufficient thermal processing during production should be used as a food safety control.
Wound botulism can be prevented by promptly seeking medical care for infected wounds, and by avoiding punctures by unsterile things such as needles used for street drug injections. It is currently being researched at USAMRIID under BSL-434.
Treatment
If diagnosed early, food-borne and wound botulism can be treated with an antitoxin that blocks the action of neurotoxin circulating in the blood. The trivalent antitoxin (effective against three neurotoxins: A, B, and E) is dispensed from quarantine stations by the U.S. government's Centers for Disease Control and Prevention (CDC). The antitoxin can prevent the disorder from worsening, but recovery still takes many weeks. Another heptavalent antitoxin (effective against seven neurotoxins: A, B, C, D, E, F, and G) may be available from the U.S. Army or FEMA. Physicians may remove whatever contaminated food is still in the gut by inducing vomiting or by using enemas. Wounds should be treated, usually surgically, to remove the source of the toxin-producing bacteria. Good supportive care in a hospital is the mainstay of therapy for all kinds of botulism.
Antitoxin is not routinely given for the treatment of infant botulism; however, a new product that recently became available from the orphan drug program can be used to treat botulism in infants. The product is comprised of immune globulins that can be given intravenously to infants who have been diagnosed with infant botulism. The new treatment is named BabyBIG (Botulism Immune Globulin, given IV) and is only currently available from a special site. Call 510-231-7600 for specific information about this treatment.
The respiratory failure and paralysis that occur with severe botulism may require a patient to be on a breathing machine (ventilator) for weeks and may require intensive medical and nursing care. After several weeks, the paralysis slowly improves as axons in the nerves are regenerated.
