The host undergoes bacteremia and subsequent death. The chest X-ray is typically without infiltrates but may reveal a widened mediastinum with pleural effusions, which may be hemorrhagic. Cutaneous anthrax occurs through entry of the spores through cuts and abrasions of the host, or via biting flies. Incubation is 2 to 5 days after exposure. The lesion is associated with an occasional severe edema, which can lead to airway compromise in the head and neck area.
Germination is at the site of exposure in the macrophages.
Locally there is edema and tissue necrosis but no purulence. The organism is easily isolated from the vesicular fluid and is evident on gram stain. The differential diagnosis includes tularemia, plague, cutaneous diphtheria, staphylococcal disease, rickettsial infection and orf, a viral disease of livestock. Antibiotics prevent dissemination but do not affect the natural history of the lesion. Gastrointestinal anthrax begins with ingestion of contaminated meat.