Anthrax
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What is it?

Anthrax is an acute infectious disease caused by the spore-forming bacterium Bacillus anthracis. Anthrax most commonly occurs in herbivorous animals (cattle, sheep, goats, camels, antelopes), plant eating animals that normally graze for food, and can be transmitted to humans by direct contact with infected animals and animal products (hides, hair and wool).

There are no known cases of human-to-human transmission of the infection. Blood and body fluids of infected individuals are not infectious.

Anthrax can enter the body through skin, by inhalation of the spores, or by ingestion of contaminated animal products (undercooked meat). Whatever the portal of entry, the symptoms are due to the actions of three toxins produced by the bacterium, namely edema factor, lethal factor and protective antigen. Due to the rapid course of inhalation disease, early diagnosis and intervention with antibiotics are essential in the management of cases of suspected inhalation anthrax.


Why is anthrax considered a potential biologic agent?

The Centers for Disease Control and Prevention (CDC) has identified anthrax as a high priority potential biologic agent. High-priority agents include organisms that have some of the following characteristics:

  • Can be easily disseminated or transmitted person-to-person
  • Cause high mortality
  • Might cause public panic and social disruption
  • Require special action for public health preparedness

Anthrax cannot be transmitted from person to person. However, it can be grown easily in large quantities. Its spores are resistant to destruction, and can theoretically be aerosolized to reach large areas and numbers of people. However, despite these feature, anthrax has never been successfully used as a biological weapon, perhaps due to the large numbers of bacterial spores required for infection and to the impact of environmental conditions on successful dissemination of spores.


Where is it found?

Anthrax is part of normal soil flora. It is endemic in Iran, Iraq, Turkey, Pakistan and sub-Saharan Africa as well as some areas of South and Central America. Anthrax also continues to cause infections in animals in the developed word. For instance, between 1963 and 1992, nine epizootics of anthrax occurred in bison herds in northern Alberta and the Northwest Territories, and outbreaks of anthrax occurred in cattle in both France and Australia in 1997. Anthrax spores can remain dormant for decades and are resistant to drying, heat, ultraviolet light, gamma radiation and many disinfectants. For these reasons, surface decontamination of the bacillus in endemic countries is considered impractical.


Who is at risk of anthrax?

Anthrax is primarily a disease of herbivores, with human infection occurring as a result of accidental contact or ingestion of infected products. Most cases of human anthrax are related to skin contact with or inhalation of anthrax spores associated with cleaning contaminated goat hair (thus the name woolsorters' disease), or contact with textiles manufactured from contaminated goat hair. There has been a significant reduction in the incidence of anthrax with decreased use of imported, contaminated raw material and immunization of textile workers. Anthrax is rare in developed countries primarily because the disease has been controlled in animals through vaccination. Those who work, or are exposed to infected animals and products in countries where anthrax is endemic, may be at increased risk of contracting the disease. This would include veterinarians, animal handlers, abattoir workers, laboratory workers, and those in the textile industries that are involved in animal hair processing.


How is it transmitted?

Soil contaminated by anthrax spores can infect grazing animals. The infection is then transmitted to humans through direct contact with infected animal tissues or the consumption of contaminated meat. The use of raw materials contaminated with anthrax spores in the manufacturing industry supports a reservoir for human infection through either direct contact or inhalation of spores.

This website has been made possible through an unrestricted educational grant from Pfizer Canada Inc.
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