Clinical Features of Patients Hospitalized for All Routes of Anthrax, 1880-2018: A Systematic Review

Abstract

Background: Anthrax is a toxin-mediated zoonotic disease caused by Bacillus anthracis, with a worldwide distribution recognized for millennia. Bacillus anthracis is considered a potential biowarfare agent.

Methods: We completed a systematic review for clinical and demographic characteristics of adults and children hospitalized with anthrax (cutaneous, inhalation, ingestion, injection [from contaminated heroin], primary meningitis) abstracted from published case reports, case series, and line lists in English from 1880 through 2018, assessing treatment impact by type and severity of disease. We analyzed geographic distribution, route of infection, exposure to anthrax, and incubation period.

Results: Data on 764 adults and 167 children were reviewed. Most cases reported for 1880 through 1915 were from Europe; those for 1916 through 1950 were from North America; and from 1951 on, cases were from Asia. Cutaneous was the most common form of anthrax for all populations. Since 1960, adult anthrax mortality has ranged from 31% for cutaneous to 90% for primary meningitis. Median incubation periods ranged from 1 day (interquartile range [IQR], 0-4) for injection to 7 days (IQR, 4-9) for inhalation anthrax. Most patients with inhalation anthrax developed pleural effusions and more than half with ingestion anthrax developed ascites. Treatment and critical care advances have improved survival for those with systemic symptoms, from approximately 30% in those untreated to approximately 70% in those receiving antimicrobials or antiserum/antitoxin.

Conclusions: This review provides an improved evidence base for both clinical care of individual anthrax patients and public health planning for wide-area aerosol releases of B. anthracis spores.

Keywords: anthrax; cutaneous anthrax; ingestion anthrax; inhalation anthrax; injection anthrax.

Figure 1.

Reported hospitalized adults with naturally occurring anthrax by region of origin and time period, 1880–2018. Injection-related cases are included in this figure, but biowarfare- and bioterrorism-related cases are not. If the exposure item/manner was unknown, we assumed it was naturally occurring anthrax. Continental regions and subregions are based on the United Nations classification of geographic regions, M49 standard. Eastern and Southeastern Asia were combined into 1 subregion, and no cases were reported from Central Asia. The highest numbers of reported cases came from the following 5 countries that are marked with diagonal lines: 290, United States; 120, United Kingdom and Northern Ireland; 69, Turkey; 52, India; and 27, Islamic Republic of Iran. Years correspond to the year of publication, not necessarily the year in which the patient was seen. One patient is missing the region of origin in the time period 1880–1915.

Figure 2.

Reported hospitalized adults with naturally occurring anthrax by route of infection and time period, 1880–2018. Injection-related cases are included in this figure, but bioterrorism- or biowarfare-related cases are not. If the exposure item/manner was unknown, we assumed it was naturally occurring anthrax. Primary meningitis is a complication with no discernible route. Route of infection was missing for 1 case in the time period 1880–1915 and 30 cases in the time period 1916–1950.