Bacillus anthracis is a rod-shaped bacterium associated with anthrax. Its life history includes a resistant dormant spore state and metabolically active growing cells. A spore is a survival state of the bacterium, not a separate species or a fungal reproductive structure. [ref]
About Anthrax by the Centers for Disease Control and Prevention. Overview: Bacillus anthracis, environmental spores and animal-associated exposure
The distinction links environmental persistence with disease ecology. Long-lived spores and actively multiplying cells have different physiological properties, so counting one state is not equivalent to measuring growth of the other. The disease also depends on the route by which exposure reaches susceptible tissue. Recognizing the species, detecting exposure and identifying an established infection are therefore separate biological questions.
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