Anthrax
A rare but serious infection caused by Bacillus anthracis; illness differs by skin, inhaled, swallowed, or injected exposure.
What causes Anthrax?
Anthrax is caused by Bacillus anthracis bacteria. People become infected when spores enter through broken skin, are inhaled or swallowed, or rarely are injected. Anthrax does not ordinarily spread from person to person.
Symptoms and what to notice
Symptoms depend on the exposure route and may include a painless skin sore with a black center, fever, severe breathing symptoms, neck swelling, abdominal illness, or extensive swelling.
How long can it last?
Symptoms may appear from one day to more than two months after exposure, depending on the route. Recovery time varies greatly with the form and severity of disease.
How serious is Anthrax?
Anthrax can become a medical emergency, especially inhalation, gastrointestinal, injection, systemic, or meningeal disease. Prompt treatment is essential.
Treatment and management
Prompt antibiotics are essential. Severe or systemic disease may require multiple intravenous antibiotics, antitoxin, pleural-fluid drainage, respiratory support, and intensive hospital care.
Vaccine: who and when?
Products: BioThrax for selected adults ages 18-65 at ongoing high risk, using a three-dose pre-exposure primary series with continuing boosters; BioThrax can also be given after exposure as three doses at 0, 2, and 4 weeks with antibiotics. CYFENDUS is a two-dose post-exposure series given two weeks apart with recommended antibiotics for eligible adults ages 18-65.
Cost note: Anthrax vaccination is not a routine retail service. It is generally supplied through an employer, laboratory program, the military, or a government-led exposure response, so a standard patient self-pay price is not available.
Trusted source
Patient cost varies by insurance, provider, location, and eligibility. Coverage and public-health access differ, so listed prices are examples rather than guaranteed patient prices. This page is for general education and does not replace individualized medical advice, diagnosis, vaccination assessment, or treatment.
Anthrax: History, Symptoms, Transmission, Treatment, Prevention, and Vaccine Information
Anthrax is a rare but potentially life-threatening disease caused mainly by the spore-forming bacterium Bacillus anthracis. The organism occurs naturally in soil and most often affects grazing animals. People can become infected after contact with an infected animal, contaminated animal products, contaminated food, or an intentionally released preparation of anthrax spores.
The illness is not a single clinical picture. Anthrax can begin in the skin, lungs, gastrointestinal tract, or deep tissue at an injection site. Each form has its own early warning signs, but any form can become systemic if bacteria or toxins spread through the bloodstream.
Anthrax deserves urgent attention because delay can allow the organism to produce toxins that cause extensive swelling, tissue injury, shock, meningitis, and organ failure. Early antibiotics greatly improve the chance of recovery, and severe disease may require antitoxin and intensive hospital care.
Important: Suspected anthrax exposure or symptoms require immediate medical and public-health assessment. This article is for general education and does not replace diagnosis, emergency advice, vaccination assessment, or treatment from qualified professionals.
Anthrax Quick Facts
| Feature | Information |
|---|---|
| Main cause | Bacillus anthracis |
| Organism type | Spore-forming, toxin-producing bacterium |
| Natural reservoir | Soil and infected grazing animals |
| Main human forms | Cutaneous, inhalation, gastrointestinal, and injection anthrax |
| Most common form | Cutaneous anthrax |
| Most dangerous classic form | Inhalation anthrax |
| Person-to-person spread | Anthrax is not generally contagious |
| Typical onset | Often 1 to 7 days, but inhalation disease may appear much later |
| Hallmark skin finding | A usually painless sore that develops a black center, called an eschar |
| Routine treatment | Prompt antibiotics selected by clinical and public-health experts |
| Treatment for severe disease | Multiple antibiotics, antitoxin, drainage or respiratory support when needed |
| U.S. pre-exposure vaccine | BioThrax for selected adults at high occupational or response-related risk |
| U.S. post-exposure vaccines | BioThrax or CYFENDUS with recommended antibiotics for eligible adults |
| Routine vaccine for the public | No |
| U.S. reporting status | Nationally notifiable disease |
What Causes Anthrax?
Most human anthrax is caused by Bacillus anthracis, a large bacterium able to form highly durable spores. Spores are a dormant survival form rather than actively growing bacteria. They can persist in suitable soil or contaminated materials for a long time and can later germinate when they enter a favorable biological environment.
The ability to form spores explains several important features of anthrax. A contaminated animal hide can remain hazardous after the animal has died. Spores can be inhaled without causing immediate symptoms. Some inhaled spores may remain dormant before germinating, which is why preventive antibiotic courses after an aerosol exposure can be prolonged.
Once spores germinate, the bacteria multiply and produce powerful toxins. The three major toxin components are protective antigen, edema factor, and lethal factor. These components work together to disrupt immune defenses, increase fluid leakage and swelling, damage tissues, and contribute to shock.
Rare anthrax-like disease can also be caused by other toxin-producing bacteria in the Bacillus cereus group. One recently recognized example is sometimes called welder’s anthrax, a severe pneumonia reported in a small number of welders and metalworkers. It is related to anthrax toxins but is not the same as typical infection with B. anthracis.
Where Does Anthrax Occur Naturally?
Anthrax is primarily a disease of animals. Cattle, sheep, goats, antelope, deer, and other grazing animals may become infected when they encounter spores in soil, water, or vegetation.
Animal outbreaks occur more often in regions where routine livestock vaccination is limited and environmental conditions allow buried spores to return to the surface. Heavy rainfall, flooding, drought, soil disturbance, or other ecological changes can sometimes precede outbreaks.
Human disease is uncommon in the United States. Risk is higher in parts of the world where anthrax in livestock remains more frequent, animals are slaughtered without veterinary inspection, or people handle hides, wool, hair, bones, meat, or other products from infected animals.
A Brief History of Anthrax
Anthrax has influenced microbiology, veterinary medicine, vaccination, occupational health, and emergency preparedness.
Early Descriptions
Diseases resembling anthrax were described long before bacteria were understood. Historical accounts reported sudden deaths among livestock and severe illness among people who worked with infected animals.
The name comes from a Greek word associated with coal, reflecting the dark center that can form in a cutaneous anthrax lesion.
The Nineteenth-Century Germ Theory Breakthrough
Anthrax became central to the development of germ theory. In the nineteenth century, researchers repeatedly observed rod-shaped organisms in the blood of animals that died from the disease.
In 1876, Robert Koch demonstrated a reproducible connection between the bacterium and anthrax. His work helped establish the idea that a specific microorganism could cause a specific disease and contributed to the principles later known as Koch’s postulates.
Pasteur and Early Vaccination
Louis Pasteur and colleagues developed an attenuated veterinary anthrax vaccine. A highly publicized 1881 demonstration in France showed that vaccinated animals survived a later challenge while unvaccinated comparison animals died.
The experiment was historically important even though modern vaccines, manufacturing standards, and testing methods are very different.
Industrial Anthrax
During the nineteenth and early twentieth centuries, inhalation anthrax became known as woolsorter’s disease. Workers handling contaminated wool, hair, and hides could inhale spores. Improved industrial hygiene, processing controls, animal-health measures, and restrictions on contaminated imports greatly reduced this occupational disease in the United States.
The Sverdlovsk Outbreak
In 1979, an accidental aerosol release from a military facility in Sverdlovsk in the former Soviet Union caused a major outbreak of inhalation anthrax. The event demonstrated the grave consequences of airborne exposure and later informed emergency-preparedness planning.
The 2001 U.S. Postal Attacks
In 2001, letters containing anthrax spores were mailed in the United States. Twenty-two people developed anthrax: 11 inhalation cases and 11 cutaneous cases. Five people died.
The attacks led to large investigations, extensive environmental cleanup, preventive treatment of exposed people, improvements in laboratory readiness, and renewed attention to anthrax as a potential biological weapon.
How Do People Get Anthrax?
The form of illness depends largely on how spores enter the body.
People may be exposed by:
- Handling an infected animal or carcass
- Handling contaminated hides, wool, hair, bone, or other animal products
- Eating raw or undercooked meat from an infected animal
- Breathing aerosolized spores in an occupational, laboratory, or intentional-release event
- Injecting a contaminated illegal drug
- Working in a laboratory with B. anthracis or potentially contaminated samples
Anthrax is not acquired from ordinary soil contact in most day-to-day settings. The overall risk for the general U.S. population is very low.
Is Anthrax Contagious?
Anthrax is not generally contagious. A person with inhalation anthrax does not spread it by coughing, sneezing, or sharing indoor air. Gastrointestinal anthrax is not ordinarily passed between people.
Standard precautions are used in healthcare. Cutaneous lesions can contain organisms, so clinicians cover draining lesions and handle dressings carefully. Public-health and infection-control professionals determine whether any additional precautions are needed.
What Is Cutaneous Anthrax?
Cutaneous anthrax occurs when spores enter through a break in the skin. It is the most common form and is usually the least deadly when promptly treated.
The lesion often begins as a small, itchy bump that can resemble an insect bite. It may develop into one or more fluid-filled blisters and then a painless ulcer with a depressed black center. Significant swelling can occur around the lesion. Nearby lymph nodes may enlarge, and fever or malaise can develop.
The head, neck, forearms, and hands are frequent sites because they are more likely to contact contaminated material.
Without treatment, cutaneous disease can spread into the bloodstream. CDC reports that up to about 20% of untreated cutaneous cases can be fatal, while almost all appropriately treated patients survive.
What Is Inhalation Anthrax?
Inhalation anthrax begins after a person breathes in spores small enough to reach deep structures in the chest. The spores are transported to lymph nodes, where they germinate and produce toxins.
Early illness can look nonspecific. Fever, chills, marked fatigue, body aches, mild cough, nausea, or heavy sweating may occur. The disease can then progress rapidly to chest discomfort, shortness of breath, confusion, shock, and respiratory failure.
Imaging may show widened tissues in the center of the chest or fluid around the lungs. Anthrax meningitis can complicate systemic infection.
Symptoms commonly begin within a week, but delayed germination means illness can appear weeks after exposure. This is why apparently well people involved in a confirmed aerosol exposure still need immediate public-health evaluation and preventive treatment.
Untreated inhalation anthrax is almost always fatal. Aggressive modern care improves survival substantially, but the disease remains a medical emergency.
What Is Gastrointestinal Anthrax?
Gastrointestinal anthrax follows the consumption of raw or undercooked meat from an infected animal. It is rare in the United States.
If infection involves the mouth, throat, or esophagus, symptoms may include a severe sore throat, painful swallowing, hoarseness, neck swelling, swollen lymph nodes, fever, and breathing difficulty.
Lower gastrointestinal infection may cause nausea, vomiting, abdominal pain, abdominal swelling, diarrhea, bloody vomit, or bloody diarrhea. Systemic spread, shock, and intestinal complications can occur.
Symptoms usually develop within several days of exposure. Because the early symptoms overlap with many more common illnesses, exposure history is especially important.
What Is Injection Anthrax?
Injection anthrax has been reported among people who injected contaminated heroin, particularly in northern Europe. It has not been reported in the United States to date.
The infection can begin deep under the skin or in muscle. Marked swelling, abscess formation, severe soft-tissue infection, sepsis, and organ failure may occur. A classic black eschar may be absent, making recognition more difficult.
Injection anthrax can spread rapidly and often requires surgery in addition to antibiotics and intensive supportive care.
What Is Anthrax Meningitis?
Anthrax meningitis occurs when systemic infection reaches the membranes and fluid surrounding the brain and spinal cord. It can complicate any form of anthrax.
Severe headache, confusion, altered consciousness, neurologic deficits, neck stiffness, or seizures are emergency warning signs. Suspected meningitis changes the antibiotic strategy because treatment must include drugs that penetrate the central nervous system.
What Is the Incubation Period?
The incubation period varies by route.
| Form | Typical timing |
|---|---|
| Cutaneous anthrax | Often 1 to 7 days after exposure |
| Gastrointestinal anthrax | Often 1 to 7 days after exposure |
| Inhalation anthrax | Commonly within a week, but delayed disease can occur up to about 2 months later |
| Injection anthrax | Variable; often develops over days |
The long outer range for inhalation disease reflects the ability of some spores to remain dormant before germinating.
What Symptoms Require Urgent Care?
Seek urgent medical care and report the possible exposure if any of the following develops after a credible anthrax exposure:
- A painless blistering sore that develops a black center
- Extensive swelling around a suspicious skin lesion
- Fever with chest pain, breathing difficulty, or heavy sweating
- Severe fatigue followed by rapidly worsening respiratory symptoms
- Bloody vomiting or bloody diarrhea
- Severe abdominal pain or abdominal swelling
- Marked neck swelling or difficulty swallowing
- Confusion, fainting, severe headache, weakness, or seizures
Do not wait for symptoms after a confirmed or strongly suspected exposure. Preventive treatment works best when started promptly.
How Is Anthrax Diagnosed?
Anthrax diagnosis combines exposure history, clinical findings, imaging, and specialized laboratory testing.
Depending on the suspected form, specimens may include:
- Blood
- Fluid or swabs from a skin lesion
- Respiratory secretions
- Pleural fluid from around the lungs
- Cerebrospinal fluid when meningitis is possible
- Tissue samples
Laboratories can test for B. anthracis by culture or molecular methods. Blood can also be evaluated for anthrax lethal factor toxin. Samples should be collected before antibiotics when this can be done without delaying treatment.
Chest radiography or CT may support a diagnosis of inhalation disease by showing mediastinal widening, lymph-node changes, or pleural effusions.
In the United States, clinicians coordinate suspected cases with hospital laboratories, state or local public-health departments, and CDC. Anthrax is nationally notifiable.
How Is Anthrax Treated?
Antibiotics are essential, but the exact regimen depends on route, severity, meningitis risk, age, pregnancy, immune status, and the organism’s susceptibility pattern.
Ciprofloxacin and doxycycline are common components of prevention and treatment plans, but serious systemic anthrax usually requires combination intravenous therapy chosen by specialists. A person should not attempt to select or use antibiotics without medical supervision.
Localized uncomplicated cutaneous anthrax may be treated with a single appropriate antibiotic. Systemic disease, inhalation disease, gastrointestinal disease, injection disease, or possible meningitis generally requires hospitalization and multiple therapies.
Supportive treatment may include:
- Intravenous fluids and medicines to support blood pressure
- Oxygen or mechanical ventilation
- Continuous drainage of pleural fluid
- Management of severe swelling
- Surgery for selected injection or soft-tissue infections
- Treatment of seizures and other neurological complications
What Are Anthrax Antitoxins?
Antibiotics kill susceptible bacteria, but they do not directly neutralize toxin already circulating in the body. For systemic anthrax, an antitoxin may be added to antibiotics.
FDA-approved products used in appropriate circumstances include monoclonal antibodies that bind anthrax protective antigen and anthrax immune globulin derived from vaccinated donors. Examples listed by FDA include:
- Raxibacumab
- Obiltoxaximab, sold as Anthim
- Anthrax immune globulin intravenous, sold as Anthrasil
These are specialized medical countermeasures rather than routine retail medicines. Public-health and infectious-disease experts guide their use.
What Is Post-Exposure Prophylaxis?
Post-exposure prophylaxis, or PEP, is treatment given before symptoms develop after a credible exposure.
For an aerosol exposure, PEP usually combines antibiotics with vaccine in eligible adults. The antibiotic component may continue for many weeks because spores can remain dormant. Current duration depends on the exposure, vaccine schedule, age, immune status, and public-health guidance.
PEP after a non-aerosol exposure may be shorter, and vaccine may not be needed when the exposure is limited to a cutaneous or ingestion route without systemic illness. These decisions require expert assessment.
Is There an Anthrax Vaccine?
Yes. Two anthrax vaccine products are licensed in the United States for specific circumstances:
| Product | Proper name | Main use | Basic schedule |
|---|---|---|---|
| BioThrax | Anthrax Vaccine Adsorbed, or AVA | Pre-exposure prevention for selected high-risk adults; also post-exposure prevention with antibiotics | Pre-exposure primary series at 0, 1, and 6 months; post-exposure doses at 0, 2, and 4 weeks |
| CYFENDUS | Anthrax Vaccine Adsorbed, Adjuvanted | Post-exposure prevention with recommended antibiotics | Two intramuscular doses given 2 weeks apart |
Both products are approved for adults 18 through 65 years of age within their labeled uses. They are not part of routine childhood or adult vaccination.
Who Should Receive BioThrax Before Exposure?
BioThrax may be recommended for adults with an ongoing high risk of exposure, such as:
- Some laboratory workers who handle high concentrations or cultures of B. anthracis
- Certain military personnel designated by the Department of Defense
- Selected workers who repeatedly handle potentially infected animals or contaminated animal products
- Certain emergency-response personnel based on job duties and risk assessment
For intramuscular pre-exposure vaccination, the FDA-labeled primary series is given at 0, 1, and 6 months. Booster doses follow for people whose risk continues.
The alternative subcutaneous schedule is used in people at risk of bleeding or hematoma from intramuscular injection and includes additional early doses. Occupational-health clinicians determine the route and schedule.
How Are Anthrax Vaccines Used After Exposure?
Vaccination after suspected or confirmed aerosol exposure is given with recommended antibiotics. Vaccine does not replace the immediate protection provided by antibiotics.
BioThrax post-exposure vaccination uses three subcutaneous doses at 0, 2, and 4 weeks.
CYFENDUS is specifically licensed for post-exposure prophylaxis. It uses two intramuscular doses, each 0.5 mL, administered two weeks apart.
Public-health authorities select the product according to availability, exposure circumstances, age, medical history, and current emergency guidance.
What Side Effects Can Anthrax Vaccines Cause?
Common reactions include pain, tenderness, warmth, redness, itching, a lump or swelling at the injection site, temporary limitation of arm movement, headache, fatigue, or muscle aches.
Serious allergic reactions are uncommon but require emergency treatment. A history of a severe allergic reaction to a previous anthrax vaccine dose or a vaccine component is a contraindication to that product.
Pregnancy, altered immune function, previous anthrax disease, and other health circumstances require individualized assessment. During a true anthrax exposure, the danger from infection can substantially change the balance of risks and benefits.
How Much Does Anthrax Vaccine Cost?
Anthrax vaccination is not a routine consumer pharmacy service. Pre-exposure vaccine is commonly supplied through an employer, laboratory program, or the military. During an emergency, vaccine and antibiotics are distributed through a coordinated public-health response.
For that reason, there is no single meaningful retail price that applies to most patients. Anyone advised to receive vaccination should ask the responsible occupational-health or public-health program about access and cost.
How Can Anthrax Be Prevented?
Prevention depends on the setting.
Animal and Agricultural Safety
- Vaccinate livestock in areas where anthrax occurs.
- Report sudden unexplained animal deaths to veterinary or agricultural authorities.
- Do not butcher, skin, or consume an animal suspected of dying from anthrax.
- Follow local guidance for safe carcass disposal and environmental control.
Occupational Safety
- Use approved biosafety practices in laboratories.
- Wear task-appropriate personal protective equipment when handling potentially contaminated animals or products.
- Follow decontamination and exposure-reporting procedures.
- Receive recommended pre-exposure vaccination when occupational risk warrants it.
Travel and Imported Products
Avoid raw or undercooked meat and unregulated animal products in areas where livestock anthrax occurs. Imported drums, hides, wool, hair, and souvenirs made from untreated animal materials can pose a risk when they come from affected regions.
Suspicious Powder or Mail
Do not shake, smell, touch, or attempt to clean a suspicious powder. Isolate the area, wash exposed skin with soap and water when instructed, and contact local emergency or law-enforcement authorities. Follow official instructions rather than improvising decontamination.
What Happens During a Public-Health Anthrax Emergency?
Authorities identify who was plausibly exposed, distribute antibiotics, offer vaccine to eligible people, and provide instructions on how long medication should continue.
People should take every dose as directed even if they feel well. Stopping early can leave a person vulnerable if dormant spores germinate later.
Anyone who develops symptoms during PEP needs immediate reassessment. Preventive medicine is not a guarantee that disease cannot occur, especially when doses are missed or vomiting prevents absorption.
Frequently Asked Questions About Anthrax
Is anthrax a virus?
No. Anthrax is caused by a bacterium, usually Bacillus anthracis.
Can you catch anthrax from another person?
Ordinary person-to-person spread does not occur. Inhalation anthrax is not spread by coughing or sharing air.
What does a cutaneous anthrax sore look like?
It can begin as an itchy bump, develop blisters, and then form a usually painless ulcer with a black center and surrounding swelling. Other skin conditions can look similar, so diagnosis requires professional assessment.
Why is the black center painless?
Toxin-mediated tissue injury can damage the local tissue while substantial swelling develops around it. Lack of pain does not mean the lesion is harmless.
How soon do anthrax symptoms appear?
Many cases begin within 1 to 7 days. Inhalation anthrax can appear later because spores may remain dormant before germinating.
Can anthrax be cured?
Yes, especially when diagnosed and treated early. Severe systemic disease remains dangerous despite treatment.
Do antibiotics prevent anthrax after exposure?
Appropriate antibiotics can prevent disease when started promptly and taken for the recommended duration. Eligible adults may also receive vaccine after an aerosol exposure.
Is ciprofloxacin always the treatment?
No. Ciprofloxacin is one important option, but the regimen depends on the form and severity of disease, susceptibility testing, patient factors, and whether meningitis is possible.
Is there a vaccine for the general public?
Anthrax vaccine is not recommended routinely for the general public. It is reserved for selected adults at increased risk or people involved in a credible exposure response.
What are the U.S. anthrax vaccine names?
The licensed products are BioThrax and CYFENDUS.
Are BioThrax and CYFENDUS interchangeable?
They have different licensed uses and schedules. BioThrax is approved for both selected pre-exposure and post-exposure use, while CYFENDUS is approved for post-exposure use with antibiotics. Public-health clinicians choose the appropriate product and schedule.
Does vaccination eliminate the need for antibiotics after exposure?
No. Post-exposure vaccination is administered together with recommended antibacterial drugs.
Can children receive anthrax vaccine?
The licensed age range is 18 through 65 years. In a major emergency, specialized government guidance would address people outside the licensed age range based on risk and available evidence.
Can pregnant people receive anthrax vaccine?
Routine pre-exposure decisions during pregnancy require individualized assessment. Following a credible exposure, infection risk can be life-threatening, so public-health and obstetric clinicians evaluate vaccination and antibiotics urgently.
Can pets or livestock get anthrax?
Yes. Anthrax primarily affects animals, especially grazing livestock and wildlife. Animal cases require veterinary and agricultural reporting and control.
Can anthrax spores survive for years?
Yes. Spores are environmentally durable and can persist for long periods under suitable conditions.
Is anthrax common in the United States?
No. Human anthrax is very rare in the United States, although occasional animal outbreaks occur.
What should I do after handling a suspicious animal hide?
Stop handling it and contact local public-health authorities for advice, particularly if the item came from a region where animal anthrax occurs or if anyone develops a suspicious skin lesion or respiratory illness.
Why is anthrax considered a bioterrorism threat?
Spores can be produced, stored, and dispersed. Aerosol exposure may initially go unnoticed, and inhalation disease can be fatal without rapid treatment. Government agencies therefore maintain detection systems, medical countermeasures, and response plans.
Why Anthrax Still Matters
Anthrax is rare, but rarity does not make it unimportant. The organism persists in nature, animal outbreaks continue, and occupational or laboratory exposures can occur. Its spores and toxins also make it a continuing emergency-preparedness concern.
The medical lesson is straightforward: exposure history matters, early treatment saves lives, and preventive antibiotics must be started promptly after a credible exposure. Vaccines add important protection for selected high-risk adults and for eligible people after an aerosol exposure.
Modern diagnosis, antibiotics, antitoxins, intensive care, occupational safeguards, livestock vaccination, and public-health preparedness have changed the outlook dramatically. Even so, suspected anthrax should never be managed casually or treated as an ordinary skin infection, stomach illness, or respiratory infection.
Medical and vaccine information reviewed against CDC and FDA guidance available through September 2026.