Anthrax

Anthrax is a notifiable condition. Bacillus anthracis spores are potential agents of biologic warfare as they are easily disseminated and are resistant to heat, light, and radiation.

Cutaneous anthrax is the most common type, accounting for the majority of cases. Inhalation, ingestion, injection, and welder’s anthrax, as well as anthrax meningitis, are less common.

Microbiology and pathology testing are used to confirm the diagnosis. Chest x-ray and computed tomography (CT) scan are useful diagnostic tools in cases of inhalation or welder’s anthrax.

Initial therapy includes treatment with empiric antimicrobial drugs and appropriate supportive therapy. Once susceptibilities are available, antimicrobial treatment may need to be modified. Anthrax antitoxins may be used in some patients.

Postexposure prophylaxis is recommended to prevent infection after known or suspected exposure to aerosolized B anthracis spores, and consists of a single antimicrobial drug (or an anthrax antitoxin as an alternative if antimicrobial drugs are not available), plus an anthrax vaccine, if indicated.

A rare zoonotic infection primarily caused by the spore-forming, gram-positive soil organism B anthracis. Cutaneous disease as a result of direct inoculation of spores through the skin is the most common manifestation and accounts for more than 95% of cases.[1]Bower WA, Yu Y, Person MK, et al. CDC guidelines for the prevention and treatment of anthrax, 2023. MMWR Recomm Rep. 2023 Nov 17;72(6):1-47. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10651316 http://www.ncbi.nlm.nih.gov/pubmed/37963097?tool=bestpractice.com However, fatal systemic illness due to spore ingestion, inhalation, or injection can occur. Exotoxin production can lead to shock, hypotension, and sudden death, necessitating early diagnosis and therapy.​ Inhalation anthrax is also known as woolsorters' disease. B anthracis is a tier 1 select agent and may be used as a bioterrorism agent.​[2]Centers for Disease Control and Prevention; United States Department of Agriculture. Federal Select Agent Program: select agents and toxins list. Jan 2025 [internet publication]. https://www.selectagents.gov/sat/list.htm

Anthrax-like illness in humans can be caused by other Bacillus cereus group pathogens. Welder's anthrax, a rare but severe and rapidly progressive anthrax-like pneumonia, is a newly identified disease that has been diagnosed in welders and metalworkers. It is caused by Bacillus species (other than B anthracis) that produce anthrax toxin. While inhalation and welder’s anthrax are similar, they are caused by different bacteria and affect different groups of people.[3]Centers for Disease Control and Prevention. Welder's anthrax: clinical overview of welder's anthrax. Dec 2025 [internet publication]. https://www.cdc.gov/welders-anthrax/hcp/clinical-overview/index.html ​ Welder’s anthrax is included as a subtype of anthrax in the anthrax case definition.[4]Centers for Disease Control and Prevention. Case data implementation resources: anthrax (Bacillus spp.) 2025 case definition. Sep 2024 [internet publication]. https://ndc.services.cdc.gov/case-definitions/anthrax