Bacillus anthracis spores. Scanning Electron Micr- ograph (SEM) of Bacillus anthracis spores. This bacterium causes anthrax in farm animals and less commonly in humans. Spores can survive dormant for many years and are resistant to extremes of heat, cold and drying. The spores 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 with antibiotics may be effective. Magnification: x10,000 at 8x10 inch size.