Seventeenth Edition, 2000

An official report of the American Public Health Association

American Public Health Association

800 I Street, NW

Washington, DC 20001-3710

[Reprinted with permission of APHA]

ANTHRAX ICD-9 022; ICD-10 A22

(Malignant pustule, Malignant edema, Woolsorter disease, Ragpicker disease)

Initial symptoms of inhalation anthrax are mild and nonspecific and may include fever, malaise and mild cough or chest pain; acute symptoms of respiratory distress, x-ray evidence of mediastinal widening, fever and shock follow in 3-5 days, with death shortly thereafter. Intestinal anthrax is rare and more difficult to recognize, except that it tends to occur in explosive food poisoning outbreaks; abdominal distress is followed by fever, signs of septicemia and death in the typical case. An oropharyngeal form of primary disease has been described.

Laboratory confirmation is made by demonstration of the causative organism in blood, lesions or discharges by direct polychrome methylene blue (M'Fadyean)-stained smears or by culture or inoculation of mice, guinea pigs or rabbits. Rapid identification of the organism by using immunodiagnostic testing, ELISA and PCR may be available in certain reference laboratories.

2. Infectious agent-Bacillus anthracis, a Gram-positive, encapsulated, spore forming, nonmotile rod.

3. Occurrence-Primarily a disease of herbivores; humans and carnivores are incidental hosts. Anthrax is an infrequent and sporadic human infection in most industrialized countries. It is an occupational hazard primarily of workers who process hides, hair (especially from goats), bone and bone products and wool; and of veterinarians and agriculture and wildlife workers who handle infected animals. Human anthrax is endemic in those agricultural regions of the world where anthrax in animals is common; these include countries in South and Central America, southern and eastern Europe, Asia and Africa. New areas of infection in livestock may develop through introduction of animal feed containing contaminated

bone meal. Environmental events such as floods may provoke epizootics. Anthrax is considered a leading potential agent in bioterrorism or biowarfare and, as such, could present in epidemiologicaily unusual circumstances.

4. Reservoir-Animals (normally herbivores, both livestock and wildlife) shed the bacilli in terminal hemorrhages or spilt blood at death. On exposure to the air, the vegetative forms sporulate, and the spores of B. anthracis, which are very resistant to adverse environmental conditions and disinfection, may remain viable in contaminated soil for many years. B. anthracis is a soil commensal in many parts of the world. Bacterial growth and spore density in soil are enhanced by flooding or other ecological conditions. Soil can also be contaminated by vultures, which spread the organism from one area to another after feeding on anthrax infected carcasses. Dried or otherwise processed skins and hides of infected animals may harbor the spores for years and are the fomites by which the disease is spread worldwide.

5. Mode of transmission-Cutaneous infection is by contact with tissues of animals (cattle, sheep, goats, horses, pigs and others) dying of the disease; possibly by biting flies that had partially fed on such animals; by contact with contaminated hair, wool, hides or products made from them, such as drums, brushes or rugs; or by contact with soil associated with infected animals or contaminated bone meal used in gardening. Inhalation anthrax results from inhalation of spores in risky industrial processes- such as tanning hides and processing wool or bone-where aerosols of B. anthracis spores may be produced. Intestinal and oropharyngeal anthrax arise from ingestion of contaminated undercooked meat; there is no evidence that milk from infected animals transmits anthrax. The disease spreads among grazing animals through contaminated soil and feed; among omnivorous and carnivorous animals through contaminated meat, bone meal or other feeds; and among wildlife from feeding on carcasses infected with anthrax. Accidental infections may occur among laboratory workers.

In 1979, an outbreak of largely inhalation anthrax occurred in Yekaterinburg (Sverdlovsk), Russia, in which 66 individuals were documented to have died of anthrax and 11 infected persons were known to have survived; many other cases are presumed to have occurred, investigations disclosed that the cases occurred as the result of a plume emanating from a biological research institute and led to the conclusion that the outbreak had resulted from an accidental aerosol generated in work related to biological warfare studies.

6. Incubation period-From 1 to 7 days, although incubation periods up to 60 days are possible. (In the Sverdlovsk outbreak, incubation periods extended up to 43 days.)

7. Period of communicability-Transmission from person to person is very rare. Articles and soil contaminated with spores may remain infective for decades.

8. Susceptibility and resistance-Uncertain; there is some evidence of inapparent infection among people in frequent contact with the infectious agent; second attacks can occur, but reports are rare.

9. Methods of control-