Botulism (BOH-chu-lih-zum) is an uncommon, nerve-paralyzing illness caused by toxins * produced by Clostridium botulinum (klos-TRIH-deum boh-chu-LIE-num) bacteria.
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What Is Botulism?
There are seven types of botulinum toxin, each designated by a letter from A through G. Only four types (A, B, E, and F) make people sick. There are three forms of naturally occurring human botulism: infant botulism, food-borne botulism, and wound botulism. Inhalation (in-huh-LAY-shun) botulism is an additional form of the illness that could possibly be spread through the air intentionally by man. Clostridium botulinum is commonly found in soil and grows best in low-oxygen environments. The bacteria form spores * that remain dormant, or inactive, waiting for conditions that allow them to grow. The spores can exist everywhere, and people might eat food containing these spores without becoming sick. When conditions are right, however, the spores can activate and produce toxin.
Food contaminated with the toxin is the culprit in cases of food-borne botulism; most outbreaks stem from food that is improperly cooked or incorrectly canned or preserved. In food-borne botulism the toxin itself is swallowed, but in cases of infant botulism an infant swallows the spores and they then activate in the intestine and produce toxin. It is believed that the infant intestine lacks enough protective intestinal bacteria, stomach acid, and immune globulins * to prevent the spores from activating. Wound botulism is rare and develops when bacteria infect a wound and grow, producing the toxin. Bioterrorists have attempted to aerosolize * botulinum toxin without success, but the threat of inhalation botulism as a biological weapon has raised concerns.
How Common Is Botulism?
More than 100 cases of botulism are reported in the United States each year. Infant botulism accounts for about 72 percent of reported cases and food-borne botulism for about 25 percent. Wound botulism is the rarest form, but health officials have noted an increase in this type in California, a rise they attribute to the intravenous * use of illegal drugs from Mexico.
* toxins are poisons that harm the body.
* spores are a temporarily inactive form of a germ enclosed in a protective shell.
* immune globulins (ih-MYOON GLAH-byoo-linz), also called gamma globulins, are the proteins of which antibodies are composed.
* aerosolize (AIR-o-suh-lize) is to put something, such as a medication, in the form of small particles or droplets that can be sprayed or released into the air.
* intravenous (in-tra-VEE-nus) means within or through a vein. For example, medications, fluid, or other substances can be given through a needle or soft tube inserted through the skin's surface directly into a vein.
How Can a Person Contract Botulism?
Botulism is not contagious. Outbreaks of food-borne botulism usually can be traced to improperly home-canned foods, especially those with low amounts of acid, such as asparagus, green beans, beets, and corn, which allow the Clostridium botulinum bacteria to grow. Various frozen foods also have been implicated in outbreaks of the disease. Most infants contract botulism by inhaling or swallowing spores; honey is one source of these spores. Wound botulism sometimes is linked to crush injuries.
What Are the Signs and Symptoms of Botulism?
The classic symptoms of botulism include blurred or double vision * , droopy eyelids, slurred speech, difficulty in swallowing, dry mouth, and muscle weakness. These symptoms appear when the toxin interrupts nerve impulses to the muscles, which paralyzes the muscles. If untreated, paralysis may progress to involve the arms, legs, trunk, and muscles of the respiratory tract * . In food-borne botulism, symptoms generally begin 18 to 36 hours after eating the contaminated food, but they can occur after as little as 6 hours or as much as 10 days. Infants with botulism may appear drowsy or sluggish, not eat well, be constipated, and have a weak cry and muscle weakness. In infants, it can take 3 to 30 days for the symptoms to appear and progress.
How Do Doctors Make the Diagnosis?
Laboratory tests can detect the toxin in blood, stool (bowel movements), or wound samples. Because the symptoms of botulism are similar to those of stroke * and several other nerve diseases, doctors also may order a brain scan, spinal tap * , or other nerve- and muscle-function tests to check for other possible causes. The doctor may ask whether the patient has eaten any home-canned foods and, if so, order tests on the suspect food.
How Is Botulism Treated?
The U.S. Centers for Disease Control and Prevention (CDC) has a supply of antitoxin * against botulism. The antitoxin can slow or halt the damage caused by botulinum toxin. The sooner it is given, the more effective it is in easing the symptoms. To help rid the body of the toxin, doctors sometimes cause vomiting or use enemas * . In severe cases, patients who are unable to breathe well enough on their own might need a ventilator (VEN-tuh-lay-ter), a machine that can help a person breathe for several weeks. Wound botulism might require surgery to remove the source of the toxin-producing bacteria.
What Are the Complications and Duration of the Disease?
Most people with botulism require hospitalization, but they typically recover after weeks or perhaps months of care. Paralysis of the respiratory muscles can lead to pneumonia * . Even after recovery, some patients may be tired and feel short of breath.
* double vision is a vision problem in which a person sees two images of a single object.
* respiratory tract includes the nose, mouth, throat, and lungs. It is the pathway through which air and gases are transported down into the lungs and back out of the body.
* stroke is a brain-damaging event usually caused by interference with blood flow to the brain. A stroke may occur when a blood vessel supplying the brain becomes clogged or bursts, depriving brain tissue of oxygen. As a result, nerve cells in the affected area of the brain, and the specific body parts they control, do not properly function.
* spinal tap, also called a lumbar puncture, is a medical procedure in which a needle is used to withdraw a sample of the fluid surrounding the spinal cord and brain. The fluid is then tested, usually to detect signs of infection, such as meningitis, or other diseases.
* antitoxin (an-tih-TOK-sin) counteracts the effects of toxins, or poisons, on the body. It is produced to act against specific toxins, like those made by the bacteria that cause botulism or diphtheria.
* enemas (EH-nuh-muhz) are procedures in which liquid is injected through the anus into the intestine, usually to flush out the intestines.
* pneumonia (nu-MO-nyah) is inflammation of the lung, usually caused by infection.
How Can Botulism Be Prevented?
Although botulinum toxin is extremely potent, it can be destroyed easily. Heating food and drinks to an internal temperature of 185 degrees
For Good and Evil
Botulinum toxin is the first biological toxin licensed for treatment of human diseases. The U.S. government approves its use to relax painfully cramped or tight muscles and as an ingredient in medications for the treatment of migraine headache, chronic lower back pain, stroke, brain injury, and cerebral palsy. Botulinum toxin injections (called Botox) can paralyze muscles that cause the skin to wrinkle. Their use is popular among people looking to maintain a youthful appearance. Ironically, the same substance has the potential to cause mass destruction if it is dispersed into the air or introduced into the food supply. The U.S. government developed botulinum toxin for potential use as a weapon during World War II. Japan, Iraq, and the Soviet Union have also experimented with botulinum toxin as a biological weapon, and Iran, North Korea, and Syria may have done so as well. However, scientists have been perplexed and terrorists thwarted by how difficult it is to prepare botulism toxin for use as a weapon. Terrorists in Japan attempted to unleash it on at least three occasions between 1990 and 1995, but their plan for widespread destruction failed each time. In addition to tracking the efforts of bioterrorists, the U.S. government has developed elaborate methods to detect and respond to an attack with botulinum toxin. A national surveillance system involving doctors and hospitals has been designed to alert the U.S. Centers for Disease Control and Prevention to botulism outbreaks, and stores of antitoxin are on hand to treat victims.