Anthrax, a zoonotic disease, is one of the earliest diseases known to man. Worldwide public health surveillance data are not accurate for either animal or human anthrax up to the 1950s, but it is probable that thousands of human cases occurred annually. Since the 1950s, it is estimated that between 2,000 and 5,000 cases of human anthrax have occurred annually.
Anthrax is seen in three forms in humans: cutaneous, inhalational, and gastrointestinal. Cutaneous anthrax begins as a blister on the skin that, within two to six days, develops into a vesicle which, when ruptured, reveals a depressed ulcer covered by a black eschar, or scab. The patient may have a mild fever and slight edema surrounding the lesion. Within one or two weeks the lesion gradually becomes covered with tissue, eventually resulting in a small scar. Treatment is with appropriate antibiotics and hygienic care of the lesion. The mortality rate without treatment is approximately 5 percent.
Inhalational anthrax is a systemic toxic disease that involves the mediastinal lymph nodes. It begins with mild respiratory symptoms, and within one or two days, fever, perspiration, and a falling blood pressure develop rapidly. The result is a toxic shock-like condition, which is followed by death in almost 100 percent of cases. Rapid intravenous treatment with antibiotics may reduce the chance of fatality.
Gastrointestinal anthrax can involve either the oropharyngeal area, which results in swelling, redness, and ulcers, or the gastrointestinal tract, with the development of ulcers, hemorrhage, and edema. With appropriate treatment, the patient recovers within approximately one week. The mortality rate is 5 to 20 percent.
Diagnosis of anthrax is made by clinical history; culturing of secretions from lesions, blood, or spinal fluid; and by epidemiological association with contaminated animal products such as wool, goat hair, hides, dried bones, and tissue from animals that have died from anthrax. Serological tests can also be diagnostic. Meningitis may develop with any form of the disease.
There is a safe and effective human anthrax vaccine. Health education is also important for people that may be exposed to diseased animals or their products. Cutaneous anthrax primarily results from occupational exposure to contaminated animal products. Such exposure may occur in the manufacturing of textiles using goat hair or wool, in handling animal hides or rendered products, and in attending to sick animals. Inhalational anthrax results from the inhalation of spores related to industrial sources. Gastrointestinal anthrax results from eating contaminated meat. A major concern today is the threat of the use of the bacterium that causes anthrax, Bacillus anthracis, as an agent in bioterrorism or biological warfare.
Animal anthrax occurs primarily in herbivores and results from ingestion of Bacillus anthracis in soil or feed. Infected animals develop gastrointestinal anthrax with systemic infection and die with secretions issuing from their bodily orifices. There is a safe and effective animal vaccine, and antibiotic treatment can be curative if started early enough.
PHILIP S. BRACHMAN
(SEE ALSO: Communicable Disease Control; Terrorism; Veterinary Public Health; Zoonoses)
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