Bacillus anthracis spores. Coloured scanning electron micrograph (SEM) of Bacillus anthracis spores. This bacterium causes anthrax in farm animals and less commonly in humans. Spores can survive for many years and are resistant to extremes of heat, cold and drying. They can then germinate to infect animals or humans. Anthrax is transmitted to humans by contact with contaminated animal hair, hides or excrement. The disease occurs in two forms, either attacking the lungs and causing pneumonia (woolsorters's disease), or the skin producing severe ulceration (malignant pustule). Treatment is with antibiotics. Magnification: x2400 at 6x4.5cm size