I.

Introduction

Botulism, potentially fatal illness caused by botulinum toxin, an extremely potent poison produced by Clostridium botulinum bacteria. The bacteria live in low oxygen environments and can contaminate food or open wounds, or can be ingested as spores. The toxin affects the nervous system, blocking signals to the muscles. It is considered the deadliest substance known—less than 1 microgram can kill a human. Without medical care, victims typically die from paralysis that stops the ability to breathe. There are over 100 cases of botulism in the United States every year, with death resulting in under 5 percent of cases.

The Clostridium botulinum organism lives in soil, and exists in different strains that produce slightly different forms of the botulinum toxin. Some strains produce toxins that only cause botulism in nonhuman animals. Other species of Clostridium bacteria have occasionally caused botulism in humans. Another group of Clostridium species can cause gangrene.

II.

Types of Botulism

A.

Food-Borne Botulism

Botulism can result from eating improperly prepared or handled food products. Most cases of food-borne botulism in the United States involve home-canned vegetables or home-preserved meats. The spores grow best in the absence of air and can thrive in sealed containers that were not adequately sterilized. Commercially prepared foods are now a rare source of this form of the disease.

B.

Wound Botulism

Botulism can occur if the Clostridium organism infects wounds from injuries, trauma, or surgery. Cases of wound botulism also have occurred among people injecting illegal drugs.

C.

Intestinal Colonization Botulism

The bacterial spores can infect the intestinal tracts of infants and sometimes adults, causing botulism. In infants under one year of age the normal microorganisms found in the intestinal tract may not have developed yet, allowing Clostridium bacteria to colonize. In adults who develop intestinal colonization botulism, the normal microorganisms may have been lost or altered after medical procedures or disease, or use of antibiotics.

D.

Other Sources

Rare cases of botulism have been reported from accidentally inhaling the botulinum toxin in a laboratory or from injecting the wrong amount of the toxin when it is used as Botox to relax wrinkles on the face for cosmetic purposes.

III.

Symptoms and Treatment

Symptoms of botulinum poisoning can appear after only a few hours but may occur over a week after exposure. From 18 to 36 hours is typical. The neurotoxin blocks nerve signals to muscles, causing paralysis. The brain functions normally but muscles in the body become flaccid or limp. Symptoms start with the face and eyes, and may include blurred vision, slurred speech, or difficulty swallowing. Muscle weakness progresses downward through the body. When the paralysis reaches the chest and diaphragm, breathing stops and the victim dies from lack of oxygen.

An antitoxin can block the effects of the toxin if given in time. The available antitoxins come from the blood serum of horses given small doses of botulinum. The horses’ immune systems produce special molecules against the toxin. Some people have serious reactions to horse serum products, however. An experimental antitoxin derived from humans is available for infants with botulism. Work on a reliable vaccine against botulism continues, but a vaccine would need to work against the multiple strains of the illness. A vaccine designed to work against five strains is available to high-risk laboratory personnel and the military, but is still in the investigational stage.

Victims may need to be put on respirators to assist breathing for six to eight weeks, and possibly up to several months. Wound botulism is also treated with penicillin.

IV.

Medical and Cosmetic Use of Toxin

In very small purified doses, the botulinum toxin can selectively paralyze muscles in medically helpful ways. Conditions treated with the toxin include spasms and tremors, and certain eye disorders.

Under the brand name Botox, the toxin is also used for cosmetic treatments. Injections can temporarily reduce wrinkles by paralyzing nerves that control muscles in the face. Users hope to have a more relaxed and youthful appearance.

V.

Biological Warfare and Terrorism

The botulinum toxin is relatively easy to produce in large quantities using Clostridium bacteria. It is also easy to transport. The extreme potency and deadliness of the toxin have made it a subject of biological warfare research. The Japanese carried out experiments on human prisoners in China during the 1930s to test the toxin. The former Soviet Union produced large stockpiles of the toxin during the Cold War. Following the Persian Gulf War of 1990 and 1991, inspectors found that Iraq under Saddam Hussein had stockpiles of botulinum toxin and a program to weaponize the toxin in bombs and warheads.

Potential terrorist attacks using the toxin are a major concern. Mass victims would need prolonged and intensive medical care. Deliberate contamination of the food supply is considered a greater risk than spreading the botulinum toxin through the air.