Rationale:

• Inhalational anthrax results in hemorrhagic mediastinitis that occurs when macrophages transport spores to the mediastinal lymph nodes where they germinate.
• Patients with inhalational anthrax are responsive to therapy if treated early in disease but have a high mortality rate (>90%) if allowed to progress.
• Hemorrhagic meningitis occurs when anthrax disseminates.
• Early recognition of inhalational anthrax is essential to saving lives.

Evidence:

• Mediastinitis was evident both in the Sverdlovsk inhalational anthrax cases and the U.S. cases of 2001. In the Sverdlovsk cases, mediastinitis was discovered on autopsies of 41 patients. Mediastinitis was confirmed by both autopsy studies and CT imaging in the 2001 outbreak (28; 29). Mediastinitis was also evident in naturally occurring cases of inhalational anthrax (30).
• Meningitis occurs frequently in inhalational anthrax. In the Sverdlovsk outbreak, pathologic investigation revealed B. anthracis in the meninges of 23 of 29 patients tested. The first case in the 2001 outbreak was diagnosed on Gram stain of the CSF, which showed gram-positive bacilli (28; 29).
• Patients with inhalational anthrax in the 2001 U.S. outbreak who were treated within 3 days of symptom onset survived (28).
• Postal workers, media employees, and certain congressional staff were at higher risk of inhalational anthrax during the 2001 anthrax outbreak in the U.S. (23).
• In a study of 47 historical cases of inhalational anthrax compared to 376 controls with community-acquired pneumonia or influenza-like illness, the most accurate predictor of anthrax disease was mediastinal widening or pleural effusion on chest x-ray. The finding was 100% sensitive for inhalational anthrax (30).

Comments:

• None.