This disease, anthrax, takes us into the world of bacteria. Bacteria are larger and more complex than viruses. The bacterium which causes anthrax is called Bacillus anthracis. It was the first disease agent to be purified, way back in 1870 by a young German G.P. called Robert Koch. Its cells are like square-ended rods about five thousandths of a millimetre long. They can change into rounded spores which can survive adverse conditions for decades.
Anthrax mainly affects herbivorous animals like cattle and sheep; the rare human cases are usually among people who handle infected animals - farmers, vets and woolpackers.
Some infected livestock can show signs of disease like staggering and convulsions very quickly, and can die due to anthrax toxins within a few days. In humans infection occurs when spores get into the skin or lungs. Skin anthrax appears as a large pus-filled blister which can cause infection of the bloodstream. Lung infection is more dangerous :: it can lead to pneumonia and internal bleeding.