botulism(redirected from toxicoinfectious botulism)
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Botulism is caused by botulinum toxin, a natural poison produced by certain bacteria in the Clostridium genus. Exposure to the botulinum toxin occurs mostly from eating contaminated food, or in infants, from certain clostridia growing in the intestine. Botulinum toxin blocks motor nerves' ability to release acetylcho-line, the neurotransmitter that relays nerve signals to muscles, and flaccid paralysis occurs. As botulism progresses, the muscles that control the airway and breathing fail.
Botulism occurs rarely, but it causes concern because of its high fatality rate. Clinical descriptions of botulism possibly reach as far back in history as ancient Rome and Greece. However, the relationship between contaminated food and botulism wasn't defined until the late 1700s. In 1793 the German physician, Justinius Kerner, deduced that a substance in spoiled sausages, which he called wurstgift (German for sausage poison), caused botulism. The toxin's origin and identity remained elusive until Emile von Ermengem, a Belgian professor, isolated Clostridium botulinum in 1895 and identified it as the poison source.
Three types of botulism have been identified: foodborne, wound, and infant botulism. The main difference between types hinges on the route of exposure to the toxin. In the United States, there are approximately 110 cases of botulism reported annually. Food-borne botulism accounts for 25% of all botulism cases and usually can be traced to eating contaminated home-preserved food. Infant botulism accounts for 72% of all cases, but the recovery rate is good (about 98%) with proper treatment. From 1990 to 2000, 263 cases of food-borne cases were reported in the United States, most of them in Alaska. Though most were related to home canning, two restaurant-associated outbreaks affected 25 people.
Though domestic food poisoning is a problem world-wide, there has been a growing concern regarding the use of botulism toxin in biological warfare and terrorist acts. The Iraqi government admitted in 1995 that it had loaded 11,200 liters of botulinum toxin into SCUD missiles during the Gulf War. Luckily, these special missiles were never used. As of 1999, there were 17 countries known to be developing biological weapons, including the culture of botulism toxins.
Causes and symptoms
Toxin produced by the bacterium Clostridium botulinum is the main culprit in botulism. Other members of the clostridium genus can produce botulinum toxin, namely C. argentinense, C. butyricum, and C. baratii, but they are minor sources. To grow, these bacteria require a low-acid, oxygen-free environment that is warm (40-120°F or 4.4-48.8°C) and moist. Lacking these conditions, the bacteria transform themselves into spores that, like plant seeds, can remain dormant for years. Clostridia and their spores exist all over the world, especially in soil and aquatic sediments. They do not threaten human or animal health until the spores encounter an environment that favors growth. The spores then germinate, and the growing bacteria produce the deadly botulism toxin.
Scientists have discovered that clostridia can produce at least seven types of botulism toxin, identified as A, B, C, D, E, F, and G. Humans are usually affected by A, B, E, and very rarely F. Domesticated animals such as dogs, cattle, and mink are affected by botulism C toxin, which also affects birds and has caused massive die-offs in domestic bird flocks and wild waterfowl. Botulism D toxin can cause illness in cattle, and horses succumb to botulism A, B, and C toxin. There have been no confirmed human or animal botulism cases linked to the G toxin.
In humans, botulinum toxin latches onto specific proteins in nerve endings and irreversibly destroys them. These proteins control the release of acetylcholine, a neurotransmitter that stimulates muscle cells. With acetylcholine release blocked, nerves are not able to stimulate muscles. Ironically, botulinum toxin has found a beneficial niche in the world of medicine due to this action. Certain medical disorders are characterized by involuntary and uncontrollable muscle contractions. Medical researchers have discovered that injecting a strictly controlled dose of botulinum toxin into affected muscles inhibits excessive muscle contractions. The muscle is partially paralyzed and normal movement is retained. This is commonly referred to as Botox injection.
The three types of human botulism include the following symptoms:
- Food-borne. Food that has been improperly preserved or stored can harbor botulinum toxin-producing clostridia. Botulism symptoms typically appear within 18-36 hours of eating contaminated food, with extremes of four hours to eight days. Initial symptoms include blurred or double vision and difficulty swallowing and speaking. Possible gastrointestinal problems include constipation, nausea, and vomiting. As botulism progresses, the victim experiences weakness or paralysis, starting with the head muscles and progressing down the body. Breathing becomes increasingly difficult. Without medical care, respiratory failure and death are very likely.
- Infant. Infant botulism was first described in 1976. Unlike adults, infants younger than 12 months are vulnerable to C. botulinum colonizing the intestine. Infants ingest spores in honey or simply by swallowing spore-containing dust. The spores germinate in the large intestine and, as the bacteria grow, they produce botulinum toxin that is absorbed into the infant's body. The first symptoms include constipation, lethargy, and poor feeding. As infant botulism progresses, sucking and swallowing (thus eating) become difficult. A nursing mother will often notice breast engorgement as the first sign of her infant's illness. The baby suffers overall weakness and cannot control head movements. Because of the flaccid paralysis of the muscles, the baby appears "floppy." Breathing is impaired, and death from respiratory failure is a very real danger.
- Wound. Confirmed cases of wound botulism have been linked to trauma such as severe crush injuries to the extremities, surgery, and illegal drug use. Wound botulism occurs when clostridia colonize an infected wound and produce botulinum toxin. The symptoms usually appear four to 18 days after an injury occurs and are similar to food-borne botulism, although gastrointestinal symptoms may be absent.
Acetylcholine — A chemical released by nerve cells to signal other cells.
Antitoxin — A substance that inactivates a poison (e.g., toxin) and protects the body from being injured by it.
CT scan — The abbreviated term for computed or computerized axial tomography. The test may involve injecting a radioactive contrast into the body. Computers are used to scan for radiation and create cross-sectional images of internal organs.
Electromyographic test — A medical test which determines if a muscle's response to electrical stimuli. The test results allow medical personnel to assess how nerves to the muscle are functioning.
Flaccid paralysis — Paralysis characterized by limp, unresponsive muscles.
Lumbar puncture — A procedure in which a small amount of cerebrospinal fluid is removed from the lower spine. Examination of this fluid helps diagnose certain illnesses.
MRI — The abbreviated term for magnetic resonance imaging. MRI uses a large circular magnet and radio waves to generate signals from atoms in the body. These signals are used to construct images of internal structures.
Neurotransmitter — A chemical found in nerves that relays nerve signals to other cells. Acetylcholine is a neurotransmitter.
Sepsis — The presence of infection-causing organisms or associated toxins in the blood or within body tissues.
Spores — A state of "suspended animation" that some bacteria can adopt when conditions are not ideal for growth. Spores are analogous to plant seeds and can germinate into growing bacteria when conditions are right.
Toxin — A poisonous substance produced by a microorganism, plant, or animal.
Tracheostomy — The procedure used to open a hole in the neck to the trachea, or windpipe. It is sometimes used in conjunction with a respirator.
Diagnosis of botulism can be tricky because symptoms mimic those presented by other diseases. Botulism may be confused with Guillain-Barre syndrome, myasthenia gravis, drug reactions, stroke, or nervous system infection, intoxications (e.g. carbon monoxide or atropine), or shellfish poisoning. Sepsis is the most common initial diagnosis for infant botulism. Failure to thrive may also be suspected. Some reports have linked infant botulism to 5-15% of sudden infant death syndrome (SIDS, crib death) cases. Laboratory tests are used for definitive diagnosis, but if botulism seems likely, treatment starts immediately.
While waiting for laboratory results, doctors ask about recently consumed food and work to dismiss other disease possibilities. A physical examination is done with an emphasis on the nervous system. As part of this examination, CT scans, MRIs, electromyographic tests, or lumbar punctures may be ordered. Laboratory tests involve testing a suspected food and/ or the patient's serum, feces, or other specimens for traces of botulinum toxin or clostridia.
Adults with botulism are treated with an antitoxin derived from horse serum that is distributed by the Centers for Disease Control and Prevention. The antitoxin (effective against toxin types A, B, and E) inactivates only the botulinum toxin that is unattached to nerve endings. Early injection of antitoxin (usually within 24 hours of onset of symptoms) can preserve nerve endings, prevent progression of the disease, and reduce mortality.
Infants, however, cannot receive the antitoxin used for adults. For them, human botulism immune globulin (BIG) is available in the United States through the Infant Botulism Treatment and Prevention Program in Berkeley, California. BIG neutralizes toxin types A, B, C, D, and E before they can bind to nerves. This antitoxin can provide protection against A and B toxins for approximately four months. Though many infants recover with supportive care, BIG cuts hospital stay in half, and therefore reduces hospital costs by 50% as well.
Aside from antitoxin, no drugs are used to treat botulism. Antibiotics are not effective for preventing or treating botulism. In fact, antibiotic use is discouraged for infants because dying bacteria could potentially release more toxin into a baby's system. Antibiotics can be used, however, to treat secondary respiratory tract and other infections.
Treatment for infants usually involves intensive respiratory support and tube feeding for weeks or even months. Once an infant can breathe unaided, physical therapy is initiated to help the child relearn how to suck and swallow. A respirator is often required to help adult patients breathe, and a tracheostomy may also be necessary.
Surgery may be necessary to clean an infected wound and remove the source of the bacteria that is producing the toxin. Antimicrobial therapy may be necessary.
When botulism is caused by food, it often is necessary to flush the gastrointestinal tract (gastric lavage). Often cathartic agents or enemas are used. It is important to avoid products that contain magnesium, since magnesium enhances the effect of the toxin.
With medical intervention, botulism victims can recover completely, though slowly. It takes weeks to months to recover from botulism, and severe cases can take years before a total recovery is attained. Recovery depends on the nerve endings building new proteins to replace those destroyed by botulinum toxin.
Vaccines against botulism do not exist to prevent infant botulism or other forms of the disease. However, scientists announced in 2004 that they had successfully vaccinated mice and ducks against type C and D, which may help lead to vaccines for humans. Food safety is the surest prevention for botulism. Botulinum toxin cannot be seen, smelled, or tasted, so the wisest course is to discard any food that seems spoiled without tasting it. Home canners must be diligent about using sterile equipment and following U.S. Department of Agriculture canning guidelines. If any part of a canned food container is rusty or bulging, the food should not be eaten. Infant botulism is difficult to prevent, because controlling what goes into an infant's mouth is often beyond control, especially in regard to spores in the air. One concrete preventive is to never feed honey to infants younger than 12 months since it is one known source of botulism spores. As infants begin eating solid foods, the same food precautions should be followed as for adults.
Cadou, Stephanie G. "Diagnosing Infant Botulism." The Nurse Practitioner 26, no.3 (March 2001): 76.
Shapiro, Roger L. and David L. Swerdlow. "Botulism: Keys to Prompt Recognition and Therapy." Consultant (April 1999): 1021-1024.
Sobel, Jeremy, et al. "Foodborne Botulism in the United States, 1990–2000." Emerging Infectious Diseases (September 2004): 1606-1612.
"Vaccination With Botulinum Neurotoxin Fragments Prevents Botuism." Obesity, Fitness & Wellness Week (August 7, 2004): 117.
1. any poisoning caused by Clostridium botulinum in the body; it produces a neurotoxin called botulinum toxin.
2. specifically, a rare but severe, often fatal, form of food poisoning due to ingestion of improperly canned or preserved foods contaminated with Clostridium botulinum. Called also foodborne botulism. Symptoms include vomiting, abdominal pain, headache, weakness, constipation, and nerve paralysis (causing difficulty in seeing, breathing, and swallowing), with death from paralysis of the respiratory organs. To prevent botulism, home canning and preserving of all nonacid foods (that is, all foods other than fruits and tomatoes) must be done according to proper specific directions.
Treatment. Treatment is determined based on the type of botulism, but careful respiratory assessment and support are always required. An antitoxin to block the action of toxin circulating in the blood can be used for foodborne and wound botulism if the problem is diagnosed and treated early.
foodborne botulism botulism (def. 2).
infant botulism that affecting infants, typically 4 to 26 weeks of age, marked by constipation, lethargy, hypotonia, and feeding difficulty; it may lead to respiratory insufficiency. It results from toxin produced in the gut by ingested organisms, rather than from preformed toxins.
wound botulism a form resulting from infection of a wound with Clostridium botulinum.
Food poisioning usually caused by the ingestion of the neurotoxin produced by the bacterium Clostridium botulinum from improperly canned or preserved food; mainly affects humans, chickens, water fowl, cattle, sheep, and horses; characterized by paralysis in all species; can be fatal; pigs, dogs, and cats are somewhat resistant. In some cases (for example, in infants) botulism may be formed in the gastrointestinal tract by ingested organisms.
See also: Clostridium botulinum.
See also: Clostridium botulinum.
[L. botulus, sausage]
A severe, sometimes fatal food poisoning caused by ingestion of food containing botulin and characterized by nausea, vomiting, disturbed vision, muscular weakness, and fatigue.
botulismA potentially fatal condition characterised by paralysis caused by a potent neurotoxin produced by Clostridium botulinum under anaerobic conditions, either linked to canned food or acquired via wounds.
Progressive dizziness, blurred vision, slurred speech, dysphagia, nausea, decreased gag reflex.
Infant botulism, food-borne botulism, wound botulism, idiopathic.
botulismA paralyzing disease caused by a potent toxin produced by C botulinum under anaerobic conditions, which is either foodborne or is acquired via wounds Clinical Progressive dizziness, blurred vision, slurred speech, dysphagia, nausea, ↓ gag reflex Clinical forms Infant botulism, food-borne botulism, wound botulism, idiopathic Treatment Botulism antitoxin
Food poisoningcaused by the ingestion of the neurotoxin produced by Clostridium botulinum and related bacteria, usually in improperly canned or preserved food; causes paralysis and can be fatal; can also result from inhalation of preformed botulinum toxin.
See also: Clostridium botulinum
See also: Clostridium botulinum
[L. botulus, sausage]