Anthrax is an acute bacterial infection caused by Bacillus anthracis — a spore-forming bacterium. It primarily infects livestock and wildlife; humans are accidentally infected through contact with animals, animal products or contaminated soil. Anthrax can occur in three forms depending on how spores enter the body: cutaneous (skin contact — most common); inhalation (breathing spores — most dangerous); and gastrointestinal (eating contaminated meat). It is both a neglected tropical disease in endemic areas and a potential bioterrorism agent.

How is anthrax transmitted?

Anthrax is not transmitted person-to-person. Transmission routes: cutaneous — contact with infected animal hides, wool, bone meal or carcasses during agricultural/industrial work; inhalation — breathing B. anthracis spores in contaminated environments or from deliberate release; gastrointestinal — eating infected, undercooked meat. Spores are the infectious form — they persist in soil for decades and can resist ordinary disinfection. Decomposing anthrax carcasses contaminate the soil, creating permanent anthrax foci.

What is the most dangerous form?

Inhalation anthrax — historically called "woolsorter's disease" (from industrial exposure in textile mills handling raw wool) — is the most lethal form. Spores inhaled into the lung are phagocytosed by alveolar macrophages, transported to mediastinal lymph nodes, and germinate there into vegetative bacteria that release lethal and edema toxins. The toxins cause massive tissue damage, pleural effusions, mediastinal widening (visible on chest X-ray — a key diagnostic clue) and haemorrhagic meningitis. Untreated mortality: 80-90%; even with treatment, mortality remains high (45-50%) if started late.

What happened in the 2001 anthrax letter attacks?

In the weeks after the September 11 attacks, letters containing refined B. anthracis spore powder were mailed to US senators and media organisations. 22 people developed anthrax: 11 cutaneous, 11 inhalation. Five people died — all from inhalation anthrax. The attacks triggered massive public health responses: prophylactic ciprofloxacin for approximately 30,000 people potentially exposed; decontamination of postal facilities and government buildings; anthrax vaccine stockpile expansion. The perpetrator was identified as biodefence researcher Bruce Ivins.

How is anthrax treated?

First-line: ciprofloxacin (500mg BD orally or 400mg IV BD for severe disease) or doxycycline (100mg BD). Duration: 60 days for inhalation anthrax (spores may persist in lung macrophages and germinate for weeks). Adjunctive antitoxin (raxibacumab or obiltoxaximab — monoclonal antibodies targeting protective antigen): added for inhalation anthrax to neutralise circulating toxin. Supportive care: aggressive management of septic shock, pleural effusions (pleural drainage may be needed).

Is anthrax relevant to Georgia?

Yes — Georgia and the South Caucasus have documented anthrax in livestock, with periodic cases reported. The region's agricultural sector (cattle, sheep grazing) creates potential for sporadic human exposure. Veterinary authorities conduct livestock anthrax vaccination programmes. PHIG monitors zoonotic disease including anthrax. Healthcare providers should consider anthrax in cases of rapidly progressive haemorrhagic fever with mediastinal widening, or characteristic painless oesophageal ulcer with oedema.

How does GMJ News cover anthrax?

GMJ News covers WHO anthrax data, the 2001 US bioterrorism attacks, clinical forms and differential diagnosis, ciprofloxacin treatment evidence, livestock vaccination strategies, anthrax relevance in the Caucasus, and the biodefence response. Anthrax illustrates both the One Health and global health security dimensions of zoonotic NTDs.

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Anthrax

GMJ News knowledge hub · last reviewed September 2026 · Georgian Medical Journal

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Anthrax — caused by Bacillus anthracis — is both a natural zoonosis (causing approximately 1,000-2,000 human cases/year from contact with infected livestock) and a WHO Neglected Tropical Disease and CDC Category A bioterrorism agent, as demonstrated by the 2001 US anthrax letter attacks that killed 5 people and showed the potential for deliberate spore weaponisation (WHO). Three clinical forms of anthrax cause strikingly different presentations: cutaneous anthrax (most common — a characteristic black eschar); inhalation anthrax (most lethal — initially resembling influenza, progressing to mediastinal widening and death within days); and gastrointestinal anthrax (from eating undercooked infected meat). The Caucasus region including Georgia has documented anthrax in livestock, making occupational exposure relevant.

Key messages

Three clinical forms — bioterrorism and NTD

Anthrax causes three distinct clinical forms depending on exposure route: cutaneous (most common — characteristic black eschar); inhalation (most lethal — widened mediastinum, rapid death without treatment); and gastrointestinal. B. anthracis is a CDC Category A bioterrorism pathogen.

Spores — the key to danger

B. anthracis produces highly resistant spores that persist in soil for decades. Spores are the infectious form for humans — entering through skin abrasions, inhalation or ingestion. The 2001 anthrax letter attacks used refined spore powder to infect postal workers, politicians and media.

WHO NTD in endemic areas

Natural anthrax (zoonotic) remains endemic in parts of Africa, Central Asia, Southern Europe and the Americas — where soil spore contamination in grazing areas infects cattle, sheep and goats. The Caucasus/Central Asia has documented anthrax in livestock, making it relevant to Georgia.

Ciprofloxacin or doxycycline for 60 days

Anthrax treatment: ciprofloxacin (500mg BD) or doxycycline (100mg BD) — for 60 days total in inhalation anthrax (spores may persist in lungs). Anthrax antitoxin (raxibacumab, obiltoxaximab) reduces toxin-mediated damage in severe disease. Early treatment is critical.

B. anthracis toxins cause most pathology

B. anthracis produces three proteins that form two exotoxins: lethal toxin (LT — kills macrophages) and edema toxin (ET — promotes fluid accumulation). These toxins cause most of the pathology of anthrax — continuing to damage even when bacteria are killed by antibiotics.

Animal vaccination prevents human disease

Livestock vaccination in endemic areas — using live attenuated Sterne strain vaccines for animals — prevents human anthrax by eliminating the animal reservoir. Regular vaccination of at-risk livestock is the primary zoonotic prevention strategy.

Key statistics

1,000-2,000

naturally acquired anthrax cases/year globally

WHO

deaths in 2001 US anthrax letter attacks (22 cases)

CDC/History

80-90%

mortality of untreated inhalation anthrax

WHO

20%

mortality of untreated cutaneous anthrax

WHO

60 days

antibiotic duration for inhalation anthrax

WHO/CDC

Decades

B. anthracis spores survive in soil

WHO

Anthrax clinical forms — incidence, mortality and mechanism

Source: WHO. Cutaneous most common; inhalation most lethal; gastrointestinal from infected meat.

Glossary of key terms

Bacillus anthracis
WHOA Gram-positive, spore-forming, rod-shaped bacterium — the causative agent of anthrax. Produces highly resistant endospores that persist in soil and on dried animal hides for decades to centuries. Virulence factors: two plasmids (pXO1 — encodes toxin; pXO2 — encodes capsule).

Anthrax lethal toxin (LT) and edema toxin (ET)
WHO/ResearchTwo exotoxins formed by combining a shared protective antigen (PA) with either lethal factor (LF) or edema factor (EF). LT: kills macrophages (causing immune evasion) and promotes septic shock. ET: adenylate cyclase that floods cells with cAMP, causing tissue edema and impairing immune function.

Inhalation anthrax (Woolsorter's disease)
WHO/CDCContracted by inhaling B. anthracis spores — historically in wool sorters handling contaminated animal hides; in bioterrorism settings, from weaponised spore aerosols. Biphasic: flu-like prodrome (2-5 days) → sudden deterioration with mediastinal widening, haemothorax, meningitis, septic shock. Mortality 80-90% without treatment; high even with treatment if started late.

Cutaneous anthrax
WHOThe most common form — spores enter skin through cuts/abrasions during contact with infected animals or hides. Pathognomonic lesion: painless papule → vesicle → central ulcer with black necrotic eschar surrounded by massive painless oedema. Untreated: approximately 20% mortality; with antibiotics, <1%.

Anthrax antitoxin
FDA/CDCRaxibacumab (anti-PA mAb) and obiltoxaximab (anti-PA mAb) — approved by FDA for inhalation anthrax in combination with antibiotics. Neutralise protective antigen (PA) and prevent toxin formation. Used when clinical response to antibiotics alone appears insufficient.

B. anthracis as bioterrorism agent
CDC/WHOB. anthracis is a Category A bioterrorism agent — the highest-priority because: it can be aerosolised; spores are stable; inhalation causes severe, potentially lethal disease; large quantities could be produced; it would cause widespread panic. The 2001 US anthrax letter attacks remain the most significant bioterrorism attack in US history.

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