In the 18th and 19th centuries anthrax in its epidemic form was not too rarely seen on the European continent. It was not until 1849 that the German bacteriologist Robert Koch demonstrated that the epidemiological origin of anthrax was bacterial.
Later on, Louis Pasteur was able to produce the effective vaccine.
Cases of anthrax are still seen in Southern and Central America, Southern and Eastern Europe, in Africa, Asia, and in the Middle East, primarily in agricultural areas and areas where livestock is present.
Human disease commonly results from exposure to contaminated animals or animal byproducts. There have even been reports of humans catching the disease by using shaving brushes made from horsehair, or by having contact with leather or other materials from contaminated animals. Cases of human infection through direct or indirect contact with contaminated individuals are extremely rare.
The anthrax bacterion (baccillus anthracis) is a non-moveable gram-positive bacillus. Being a facultative anaerobic bacterion it has the ability to live in normal oxygen concentrations as well as in the absence of oxygen. The optimal temperature for bacterial growth is around 35 degrees Cp. Increasing temerature to 42 - 43 degrees C will result in considerable bacterial weakening because of the loss of its surrounding polypeptide capsule. Outside the body anthrax bacteria have the ability to dry up into an extremely resistant spore, witch can survive for many years in nature. Spores form in the soil and can be carried away with the wind, travelling long distances. Spores usually have to be burned, or destroyed through autoclaving, an effective form of disinfection where the material is heated to 120 degrees C using steam pressure.
There are three presentations of anthrax known to infect humans.
- Cutaneous anthrax, malignant postule form is most common. Bacterial spores enter the body through scratches in the skin and create an elevated cutaneous wound or papule that enlarges and erodes into an ulcer. Nearby lymph nodes may be swollen. As the disease progresses, ulcerations gradually darken to purple or black, and a charcoal carbuncle is formed (anthrax meas charcoal in Greek). Typical attending symptoms are headaches, fever, and vomiting.
- Gastro-intestinal anthrax. This form is aquired by eating or drinking contaminated material, most often meat. Symptoms are loss of appetite, nausea, and vomiting, developing into stomach ache, severe diarrhoea, and vomiting blood.
- Pulmonary anthrax, wool-sorters disease, develops when spores of B. Anthracis are inhaled, and the disease progresses through the airways. Large quantities of bacteria are found in saliva. This is by far the most dangerous form of infection. The disease presents symptoms resembling a cold or the flu which after a few days develops into worsening respiratory distress or respiratory failure.
The spores of B anthracis germinate in the body to yield vegetative bacteria which multiply and release a potent necrotizing toxin. Bacterial toxins severely impair the natural defence of the immune system and its ability to fight infection. Bacteria are able to withstand attack from white blood cells. The spleen that produces the white blood cells will swell and if left untreated the patient may die of blood poisoning as anthrax toxin levels rise dramatically in the later stages of disease development.
The incubation period can vary from 2 to 6 days depending on pathology.
Untreated, mortality varies from 20% in cutaneous anthrax to 90% in pulmonary anthrax.
Anthrax spores is one of the micro-organism used in biological weapons. The effectiveness of anthrax in biological warfare is the result of a relatively high mortality compared to other bacterial infections in combination with the high durability of bacterial spores. In addition, spores are relatively easy to mount in different weapon systems making it possible to spread spores over large areas.
Anthrax spores are hardly visible and has neather smell nor taste. The presence of visible powder is therefore not an indication of anthrax spores.