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Pathology - Inhalational

Naturally occurring inhalational anthrax was historically a disease associated with wool sorters at industrial mills. Only 18 cases were reported in the US from 1900 to 1978 (6).

This form of the disease is a result of the deposition of spore-bearing particles of 1 to 5 mm into the alveolar spaces (6). Macrophages, which act as a host defense mechanism, lyse and destroy some of the spores. Infection in the lung is extremely rare (7). The surviving spores are transported to the mediastinal and peribronchial lymph nodes. Germination may occur in the mediastinal lymph nodes up to 60 days after infection. Disease immediately follows germination (6). Anthrax bacilli replicate in the lymph nodes (7). Hemorrhage, edema, and necrosis are the results of bacterial toxins released during replication. The first stage of illness is flu-like with fever, myalgia, dyspnea, cough, headache, vomiting, chills, abdominal pain, and chest pain. Sudden fever, dyspnea, diaphoresis, and shock characterize the second stage of illness. In the second stage of illness, cyanosis and hypotension result in a rapid death. Death usually results 2-3 days after the onset of symptoms. (6). Chest radiographs showing a widened mediastinum are evidence of hemorrhagic mediastinitis and pleural effusions (7). Hemorrhagic thoracic lymphadenitis and hemorrhagic mediastinitis were seen in the autopsies of patients who died after exposure to inhalational anthrax in Sverdlovsk (6).

Inhalation anthrax is the method of infection associated with biological warfare. It kills up to 80% of infected individuals within 2 to 4 days. Antibiotics are rarely a productive method of treatment unless they are administered immediately after the appearance of symptoms (1). Inhalational anthrax is 99% lethal in unvaccinated individuals (9).