Anthrax: A Systematic Review of Atypical Presentations

During the 2001 US anthrax attacks, mortality from inhalational anthrax was significantly lower than had been reported historically, which was attributed in part to early identification and timely treatment. During future attacks, clinicians will rely on published descriptions of the clinical features of inhalational anthrax to rapidly diagnose patients and institute appropriate treatment. Published descriptions of typical inhalation anthrax usually include patients presenting with cough, dyspnea, or chest pain and found to have abnormal lung examination results with pleural effusions or enlarged mediastinum. The purpose of this article is to evaluate whether atypical presentations of inhalational anthrax occur and to describe the features of these presentations. We define atypical presentations as those in patients with confirmed anthrax infection who do not have known cutaneous, gastrointestinal, or inhalational ports of entry. We reviewed the case reports of 42 patients with atypical anthrax (published between 1900 and 2004) that may have had an inhalational source of infection to evaluate whether their clinical presentations differed from the typical findings of inhalational anthrax. Patients with atypical anthrax were less likely to have cough, chest pain, or abnormal lung examination results than patients with typical inhalational anthrax (P<.05 for all comparisons). A previously published screening protocol for patients with suspected anthrax correctly identified 91% of patients with atypical presentations. We conclude that although uncommon, atypical presentations of inhalational anthrax likely occur. Timely diagnosis and treatment of patients with inhalational anthrax require clinical awareness of the full spectrum of signs and symptoms associated with inhalational anthrax.