ANTHRAX

also called splenic fever, malignant pustule, or woolsorters' disease acute, specific, infectious, febrile disease of animals, including humans, caused by Bacillus anthracis, an organism that under certain conditions forms highly resistant spores capable of persisting and retaining their virulence in contaminated soil or other material for many years. A disease chiefly of herbivores (grass eaters), the infection may be acquired by persons handling the wool, hair, hides, bones, or carcasses of affected animals. Anthrax is one of the oldest recorded diseases of animals, being mentioned by Moses in Exodus 9:9 and, among the classical authors of Greek and Roman antiquity, by Homer, Hippocrates, Ovid, Galen, Virgil, and Pliny. Devastating epidemics of the disease are recorded by many medieval and modern writers. In the 18th and 19th centuries it sometimes spread like a plague over the southern part of Europe, taking a heavy toll of human and animal life. Anthrax was the first disease of humans and other animals in which the causative agent was definitely demonstrated as a specific microorganismby the French biologist Casimir-Joseph Davaine in 1863 and in 1876 by the German bacteriologist Robert Koch, who isolated the organism in pure culture. It was also the first infectious disease against which a bacterial vaccine was found to be effective, by Louis Pasteur in 1881. These discoveries led to the origin and development of the modern sciences of bacteriology and immunology. Practically all animals are susceptible to anthrax. Cattle, sheep, goats, horses, and mules are the most commonly affected and usually acquire the disease by grazing on contaminated pastures. Outbreaks in swine, dogs, cats, and wild animals held in captivity generally result from consumption of contaminated food. The disease may occur in a peracute (extremely acute), acute, or subacute form (internal anthrax) or in a chronic or localized form (external anthrax). In the acute forms there is excitement and a rise in body temperature followed by depression, spasms, respiratory or cardiac distress, trembling, staggering, convulsions, and death. Bloody discharges sometimes come from the natural body openings, and edematous (serous fluid) swellings may appear on different parts of the body. The peracute and acute forms usually terminate in death within a day or two; the subacute form may lead to death in three to five days or longer or to complete recovery after several days. Chronic anthrax occurs mostly in swine and dogs and is characterized by marked swelling of the throat, difficult breathing, and a bloodstained frothy discharge from the mouth. Affected animals sometimes die of suffocation. Prophylactic vaccination is extensively used in preventing anthrax in livestock. During outbreaks, strict quarantine measures, disposal of diseased carcasses by burning, fly control, and good sanitation are essential in controlling the disease. Anthrax in humans occurs as a cutaneous, pulmonary, or intestinal infection; the most common type occurs as a primary localized infection of the skin in the form of a carbuncle. It usually results from handling infected material, lesions occurring mostly on the hands, arms, or neck as a small pimple that develops rapidly into a large vesicle with black necrotic centre (the malignant pustule). Should this condition become generalized, a fatal septicemia (blood poisoning) may ensue. The pulmonary form (woolsorters' disease) affects principally the lungs and pleura and results from inhaling anthrax spores in areas where hair and wool are processed. This form of the disease usually runs a rapid course and terminates fatally. The intestinal form of the disease, which sometimes follows the consumption of contaminated meat, is characterized by an acute inflammation of the intestinal tract, vomiting, and severe diarrhea. Anthrax is occasionally transmitted to humans by spore-contaminated brushes or by wearing apparel such as furs and leather goods. Prompt diagnosis and early treatment are of great importance. Antianthrax serum, arsenicals, and antibiotics are used with excellent results. The hazard of infection to industrial workers can be reduced by sterilization of potentially contaminated material before handling, protective clothing, use of respirators, and good sanitary facilities and in agricultural workers by avoiding the skinning or opening of animals that died of the disease.