Pulmonary anthrax follows rapid multiplication of spores in the mediastinal lymph nodes. Rarely, GI anthrax may follow ingestion of contaminated meat when a break is present in the pharyngeal or intestinal mucosa, which facilitates invasion of the intestinal wall. Although anthrax is an important animal disease, it is rare in humans and mainly occurs in countries that do not prevent industrial or agricultural exposure to infected goats, cattle, sheep, and horses or their products. Anthrax also occurs in exotic wildlife such as hippos, elephants, and cape buffalo. Considerable peripheral erythema, vesiculation, and induration are present.
Central ulceration follows, with serosanguineous exudation and formation of a black eschar.
Local lymphadenopathy may occur, occasionally with malaise, myalgia, headache, fever, nausea, and vomiting. Initial symptoms of pulmonary anthrax are insidious and resemble influenza. Fever increases, and within a few days, severe respiratory distress develops, followed by cyanosis, shock, and coma. Severe hemorrhagic necrotizing lymphadenitis develops and spreads to the adjacent mediastinal structures. Serosanguineous transudation, pulmonary edema, and pleural effusion occur.