- 1 Definition
- 2 Clinically Relevant Anatomy
- 3 Etiology
- 4 Epidemiology
- 5 Risk Factors
- 6 Pathophysiology
- 7 Clinical Presentation
- 8 Diagnosis
- 9 Management / Interventions
- 10 Differential Diagnosis
- 11 Resources
- 12 References
- A serious infectious disease caused by gram-positive, rod-shaped bacteria known as Bacillus anthracis.
- Anthrax can be found naturally in soil and commonly affects domestic and wild animals around the world.
- Rare in the United States - people can get sick with anthrax if they come in contact with infected animals or contaminated animal products.
- Contact with anthrax can cause severe illness in both humans and animals.
- Anthrax is not contagious, which means you can’t catch it like the cold or flu.
- Anthrax can occur in four forms: cutaneous, inhalation, gastrointestinal, and inhalation.
Watch this short video for an overview of Anthrax.
Clinically Relevant Anatomy
The pathogen that causes Anthrax is known as Bacillus anthracis, a spore- forming, rod-shaped, gram-positive bacterium.
Incidence of any anthrax infection has been less than 1 case per year in the US for the last 30 years. From 1955–1994, US cases totaled 235, with 224 cases of cutaneous anthrax, 11 cases of inhalation anthrax, and 20 fatalities.
Anthrax is common in Middle East, the Indian subcontinent, Africa, Asia, and Latin America and is rare in Western Europe. In 1958, approximately 100,000 cases of anthrax occurred worldwide. Anthrax is endemic in Africa and Asia despite vaccination programs.
In 1978, during the Rhodesian civil war, failure of veterinary vaccination programs led to a human epidemic, causing 6500 anthrax cases and 100 fatalities.
In 1982, Thailand had an outbreak of 24 cases, concurrently with 52 cases of cutaneous anthrax after ingestion of contaminated water buffalo meat.
In October 2001, 22 cases of anthrax infection were identified after being exposed to spores sent through the mail. Five of those who were infected died. Most recently in 2016, in Siberia, Russia, there was an outbreak of anthrax that affected at least 13 Siberian people and killed over 2,000 reindeer.
Occupational hazard for:
- Individuals who handle animal wool, hair, hides, or bone meal products.
- Laboratory professionals
- Mail handlers, military personnel, and response workers who may be exposed during a bioterror event involving anthrax spores
There is no racial, sexual, or age predilection for anthrax. However, because anthrax is often related to industrial exposure and farming, the disease most often affects young and middle-aged adults.
Anthrax can occur in four different forms, depending on the route of infection.
When the spores get inside the body, from any route mentioned from above, the spores then become anthrax bacteria. Then the bacteria can multiply, spread out in the body, produce toxins (poisons), and cause severe illness. 
Clinical manifestations usually happen 1-7 days after exposure from the spores.
- Small blisters/ bumps (can be itchy)
- Painless skin sore (ulcer), most often the sore will be on the face, neck, arms, or hands
- Fever and chills
- Swelling of neck and lymph node enlargement
- Oral bleeding
- Sore throat and painful swallowing
- Loss of appetite
- Respiratory distress
- Nausea and vomiting or hematemesis
- Diarrhea or bloody diarrhea
- Flushing (red face) and red eyes
- Abdominal pain
- Swelling of abdomen (stomach)
- Fever and chills
- Chest Discomfort
- Shortness of breath
- Confusion or dizziness
- Nausea, vomiting (hematemesis), or stomach pains
- Body aches
Injection anthrax has almost the same manifestation as Cutaneous Anthrax except for it could affect deeper structures and can spread more easily.
- Fever and chills
- A group of small blisters or bumps that may itch, appearing where the drug was injected
- A painless skin sore with a black center that appears after the blisters or bumps
- Redness and swelling around the sore
- Abscesses deep under the skin or in the muscle where the drug was injected
Diagnosis is made through history-taking for possible exposure, evaluation of signs and symptoms, diagnostic procedures, and laboratory findings.
The Centers for Disease Control and Prevention (CDC) has resources that can help in diagnosing and investigating anthrax. These are:
- Anthrax Case Investigation System
- Case Investigation Form
- Anthrax Investigation Database
- Case Definition
Diagnostic Procedures/ Laboratory Findings
- Gram Staining and Blood Culture
- Enzyme-Linked Immunosorbent Assay (ELISA)
- ELISA to detect immunoglobulin G (IgG) response to B anthracis protective antigen (PA) is 98.6% sensitive and 80% specific. Protective antigen–competitive inhibition ELISA is used as a second confirmatory step to improve specificity.
- Chest Radiograph
- widening of the mediastinum,paratracheal and hilar fullness, and pleural effusions
- CT Scan
- detects hemorrhagic mediastinal and hilar lymph nodes and edema, peribronchial thickening, and pleural effusions
- Lumbar Puncture
- CSF in patients with anthrax meningitis is grossly hemorrhagic with few polymorphonuclear neutrophils (PMNs) and numerous gram-positive bacilli.
- Histologic Findings
Management / Interventions
The CDC has a set of guidelines for the Prevention and Treatment of Anthrax.
- Penicillin- preferred agent used to treat nonbioterrorist anthrax
- Monoclonal Antibodies
- Raxibacumab- prophylactic agent and treatment of inhalational anthrax
- Obiltoxaximab- treatment of inhalational anthrax
- Human anthrax immune globulin (Anthrasil)- indicated for treatment of inhalational anthrax in adults and children in combination with antibiotic therapy.
- Anthrax Vaccine Adsorbed (BioThrax)- indicated for pre-exposure prophylaxis in persons at high risk of exposure and for postexposure prophylaxis following suspected or confirmed B anthracis exposure.
Patients with Anthrax infection would also benefit from physiotherapy management during their recovery phase. Physiotherapy treatments for Inhalation Anthrax would aim at chest physiotherapy and symptomatic treatment, such as:
- Percussion and vibration
- Coughing Techniques
- Breathing Exercises
- Mobilization of patient
Generally, patients may benefit from:
- General Body Conditioning Exercises
- Range of Motion Exercises
- Resistive Exercises
- Aerobic Conditioning
- Bubonic Plague
- Primary Syphyilis
- Pneumonia (Atypcial or Community- Acquired)
- Bacterial Mediastinitis
- U.S. National Library of Medicine. National Institute of Health. Medline Plus. Anthrax.http://www.nlm.nih.gov/medlineplus/anthrax.html (accessed 2 March 2011)
- CDC- Anthrax- Basic Information. Available at https://www.cdc.gov/anthrax/basics/index.html (Accessed March 30, 2020)
- Rehealthify. Anthrax- Causes, Symptoms, Treatment and More... Available at https://www.youtube.com/watch?v=9uiM2OOzx88
- Annual Reviews. 2020. Anthrax. [online] Available at: https://www.annualreviews.org/doi/full/10.1146/annurev.micro.55.1.647#_i3 [Accessed 2 April 2020].
- Medscape- Anthrax. Available at https://emedicine.medscape.com/article/212127-overview (Accessed March 31, 2020)
- Medicinenet- Anthrax. Available at https://www.medicinenet.com/anthrax/article.htm#anthrax_facts (Accessed March 31, 2020)
- Mayo Clinic- Anthrax. Available at https://www.mayoclinic.org/diseases-conditions/anthrax/symptoms-causes/syc-20356203 (Accessed April 2, 2020)