Anthrax

Anthrax, contagious disease of warm-blooded animals, including humans, caused by the bacterium Bacillus anthracis. One of the oldest known diseases, it was once epidemic and still appears in many areas of the world, but only sporadically in the western and southern United States, and Europe. It was the first disease for which the causative organism was isolated, by C. J. Davaine in 1863, for which a pure culture was obtained, by Robert Koch in 1876. An effective vaccine for anthrax was developed by Louis Pasteur in 1881.

In humans, the disease appears in both external and internal forms, with a death rate of about 20 per cent. The external or cutaneous form is contracted through cuts or abrasions in the skin by those who handle infected hides and carcasses and may be self-limiting, but often disseminates into the bloodstream, with fever and prostration. It is characterized by malignant pustules on exposed skin areas. The internal type is acquired by inhaling anthrax spores, as from animal hair and wool, which invade the lungs and sometimes the intestinal tract to cause haemorrhaging. It is thought that an intestinal variety may be caused by consuming contaminated meat or milk. Workers exposed to animal products, especially wool, are protected by vaccination. Penicillin and tetracyclines are effective in treatment except in rapidly progressing cases.

Animals acquire the disease from: drinking water draining from contaminated soil, in which the organism may live for years; from eating infected carcasses and feedstuffs; or from the bites of bloodsucking insects. The disease, sometimes manifested by staggering, bloody discharge, convulsions, and suffocation, may be fatal almost immediately in acute cases and within three to five days in subacute cases. Death is caused by toxaemia. Pre-seasonal inoculations and antibiotics are effective.

In the United States, in the aftermath of the terrorist attacks there on September 11, 2001, anthrax bacteria sent through the post by bioterrorists was discovered in a number of postal facilities, and within media companies and government buildings. Within a month 17 cases of both the skin and inhalation varieties had been reported, with 4 people dying as a result of inhalation anthrax. Those affected had either handled infected mail, or had inhaled anthrax spores that had been released once an infected envelope was opened. Massive stocks of anthrax vaccine were subsequently built up rapidly.