Anthrax

Anthrax is an acute infectious disease caused by the spore-forming bacterium Bacillus anthracis. Anthrax most commonly occurs in cattle, sheep, goats, camels, antelopes and other animals, but it can also occur in humans when they are exposed to infected animals or tissue from infected animals.

Anthrax infection can occur in three forms: coetaneous (skin), inhalation, and gastrointestinal. Anthrax spores can live in the soil for many years, and humans can become infected with anthrax by handling products from infected animals or by inhaling anthrax spores from contaminated animal products. Eating undercooked meat from infected animals can also spread anthrax.

Symptoms of disease vary depending on how the disease was contracted, but symptoms usually occur within 7 days.

Coetaneous: Most (about 95%) anthrax infections occur when the bacterium enters a cut on the skin, such as when handling contaminated wool, hides, leather or hair products (especially goat hair) of infected animals. Skin infection begins as a raised itchy bump that resembles an insect bite but within 1-2 days develops into a vesicle and then a painless ulcer, usually 1-3 cm in diameter, with a characteristic black area in the centre. Lymph glands in the adjacent area may swell. About 20% of untreated cases of coetaneous anthrax will result in death. Deaths are rare with appropriate ant microbial therapy.

Inhalation: Initial symptoms may resemble a common cold. After several days, the symptoms may progress to severe breathing problems and shock. Inhalation anthrax is usually fatal.

Intestinal: The intestinal disease form of anthrax may follow the consumption of contaminated meat and is characterized by an acute inflammation of the intestinal tract. Initial signs of nausea, loss of appetite, vomiting, fever are followed by abdominal pain, vomiting of blood, and severe diarrhoea. Intestinal anthrax results in death in 25% to 60% of cases.

A lethal dose of anthrax is considered to be 10,000 spores; 80 percent of a population that inhaled such a dose would die. Less than one millionth of a gram is invariably fatal within five days to a week after exposure. According to the web-sight www.fas.org an estimate by the US Congress's Office of Technology Assessment shows that; 100 kilograms of anthrax, released from a low-flying aircraft over a large city on a clear, calm night, could kill one to three million people.

Direct person-to-person spread of anthrax is extremely unusual. In countries where anthrax is common and vaccination levels of animal herds are low, humans should avoid contact with livestock and animal products and avoid eating meat that has not been properly slaughtered and cooked. Also, an anthrax vaccine has been licensed for use in humans. The vaccine is reported to be 93% effective in protecting against anthrax.
By: Åsa Bergqvist Widolf, June 2001 <<back | top