Bacillus Anthracis (Anthrax)
Anthrax isinfectious disease caused by the spore-forming bacterium Bacillus anthracis.
The word “anthrax” is derived from the Greek word for “coal” or “black” because of the characteristic coal-black sore. It causes dark, coal-like structure on affected areas.
Anthrax mainly affects animals. People get infected through contact with an infected animal or by inhaling spores of bacterium. It can cause severe disease in both humans and animals.
Koch uses Bacillus anthracis as the model to develop his famous Koch Postulates.
Epidemiological Triad
Agent – The causative agent of Anthrax by gram-positive, rod-shaped bacteria Bacillus anthracis.
Host– Any age group, highest number of cases was found in the age group of 30 -59 years.
Environment – Found naturally in soil, infected animals or contaminated animal products, soil containing spores of anthrax.
Types of Anthrax
Bacillus anthracis develops illness a depends on how anthrax enters the human body. Typically, anthrax enters the body through the lungs, gastrointestinal system, or skin.
In humans, three types of anthrax infection occurs –
1. Inhalation anthrax
2. Gastrointestinal anthrax
3. Cutaneous anthrax
1. Inhalation Anthrax
Inhalation anthrax is considered as a most serious form of anthrax. When a people breathe the anthrax spores, it develops inhalation anthrax.
Inhalation anthrax associated with people who work in places such as wool sorters; wool mills, slaughterhouses, and tanneries (leather) may inhale spores of bacteria when they working with infected animals or contaminated animal products from infected animals.
Inhalation anthrax primarily develops in the lymph nodes in the chest before spreading throughout the rest of the body. It causes severe breathing problems and shock. Without treatment, inhalation anthrax can be fatal.
2. Gastrointestinal Anthrax
When a people consuming raw or undercooked meat from an animal infected with anthrax, it can develop gastrointestinal anthrax.
Once ingested, anthrax spores can affect the upper gastrointestinal tract such as; throat, esophagus, stomach, and first part of the small intestine (duodenum) lead to develop variety of symptoms.
3. Cutaneous Anthrax
Cutaneous anthrax infection is the most common form of anthrax. When anthrax spores get into the skin, usually through a cut, wound, or scrape, a person can develop cutaneous anthrax.
It usually develops from 1 to 7 days after exposure to the infection.
4. Injection Anthrax
Injection Anthrax rare disease that affects heroin-injecting drug users and is caused by a bacterium Bacillus anthracis.
Infection develops deep under the skin or in the muscle where the drug was injected. The infection can spread faster throughout the body and may be harder to recognize and treat.
infection in injection site or skin in a drug user does not necessarily person has anthrax because lots of other more common bacteria can cause skin and injection site infections.
Mode of Transmission
People get infected with anthrax –
1. Breathing in spores
2. Consuming food or drinking water that is contaminated with spores
3. Getting spores in a cut, wound, or scrape in the skin
Animals get infected with anthrax –
1. Breathe in spores
2. Ingest spores in contaminated soil, plants, or water
Clinical Manifestation
A. Clinical manifestation of inhalation Anthrax
Clinical manifestations for pulmonary anthrax will appear 1 – 7 days.
Inhalation anthrax symptoms can include-
1. Fever and chills
2. Myalgia- muscle pain, Body aches
3. Dyspnea – Shortness of breath
4. Cough
5. Headache
6. Nausea, vomiting, Extreme tiredness
7. Abdominal pain
8. Diaphoresis- Sweats
8. Cyanosis
9. Thoracic lymphadenitis (enlargement in one or more lymph nodes)
10. Chest Discomfort
12. Confusion or dizziness
B. Clinical manifestation of Gastrointestinal Anthrax
GI Anthrax is associated with ingesting undercooked contaminated meat. Clinical manifestations will appear 2 – 5 days after ingestion.
Gastrointestinal Anthrax symptoms can include-
1. Acute Abdominal pain
2. Nausea and vomiting, especially bloody vomiting
3. Malaise
4. Diarrhea or bloody diarrhea
5. Ascitis
6. Fever and chills, Headache
7. Swelling of neck or neck glands
8. Sore throat
9. Painful swallowing
10. Hoarseness.
11. Flushing (red face) and red eyes
12. Swelling of abdomen (stomach)
Mortality in are high in gastrointestinal anthrax because of Intestinal perforation or anthrax toxaemia. It kills the cells and leading to tissue damage, bleeding and death.
The morbidity due to loss of blood, electrolyte imbalance and subsequent shock.
C. Clinical manifestation of Cutaneous Anthrax
Cutaneous Anthrax occurs, when cuts, wound or breaks in the skin , is exposed to anthrax infected animals or infected animal product.
Cutaneous Anthrax symptoms can include-
1. Macular and papular skin lesions
2. Itching of group of small blisters or bumps
3. Vesicles that discharge clear or serosanguinous fluid (contains both blood and liquid)
4. Painless black eschar – painless skin sore (ulcer) with a black center that appears after the small blisters or bumps
5. Painful lymphadenopathy
6. Swelling around the sore
7. Most often sore occurs on the face, neck, arms, or hand
D. Clinical manifestation of Injection Anthrax
Symptoms can include-
1. Fever and chills
2. Painless skin sore with a black centered, appears after the blisters or bumps
3. Swelling around the sore
4. Abscesses formed deep under the skin or in the muscle where the drug was injected
5. Group of small blisters or bumps may be an itch, appearing where the drug was injected
Lab Diagnosis
Samples for lab diagnose must be taken before the patient start taking antibiotics for treatment.
1. To measure the antibodies or toxin in blood
2. To test directly for Bacillus anthracis in a specimen –
a. Blood
b. Skin lesion swab
c. Spinal fluid
d. Respiratory secretions
Pathophysiology
1. People get infected with anthrax when spores enters into the body through broken skin or mucous membranes.
2. When anthrax spores enter inside the body, they germinate in macrophages and become activated. They replicate in lymph nodes and intracellular space.
3. Bacteria produce antiphagocytic capsule, bacteria multiplied, and spread out in the body, produce toxins (poisons), and cause severe illness.
4. Production of bacterial toxins causes tissue destruction and lead to edema.
Anthrax Risk Factors
1. When person come in direct contact with anthrax spores, contract to anthrax infection.
2. A person who live or employed an area with a high risk of exposure to anthrax
3. Personnel who work with anthrax in a laboratory setting
4. Person handles animal skins, furs or wool from areas with a higher incidence of anthrax.
5. Work in veterinary medicine
6. Handle or dress animals
7. Inject illegal drugs, such as heroin users
Treatment of Anthrax
Treatment for anthrax includes administration of antibiotics, vaccination or treatment with antibody to the toxin.
Pharmacological therapy for bacillus anthracis infection –
1. Antibiotics therapy
All types of anthrax infection can be treated with antibiotics, including intravenous antibiotics.
Penicillin V oral tablet
Penicillin G
Streptomycin
Tetracycline
Erythromycin
Erythromycin lactobionate
Chloramphenicol
Ciprofloxacin
Doxycycline
2. Antitoxin therapy
After anthrax toxins released in the body, treatment with antibody to the toxin (antitoxin). Antitoxins target anthrax toxins in the body.
Anthim of antitoxins that can be used for treating anthrax.
3. Corticosteroid therapy for severe edema
Dexamethasone is an anti-inflammatory medication used specifically to decrease swelling (edema).
Doxycycline is not recommended for use in children under age of 9 years, it may result in retarded skeletal growth and risk of yellow tooth discolouration in young children.
4. Vaccination
Reduce your risk of anthrax by having the anthrax vaccine
Vaccination given in a series of six shots initial doses at 0, 2, and 4 weeks, and 6 months, 12 months and 18 months with yearly boosters to maintain immunity after initiation of the primary series.
Prevention and Control
1. Vaccination is necessary to prevent anthrax in humans and animals
2. Diagnosis and Treatment – Postexposure prophylaxis; Doxycycline, Ciprofloxacin is recommended.
3. Practice good hand hygiene
4. Avoid direct contact with infected or contaminated materials. Use protective clothing such as gloves, boots, and coveralls as appropriate.
5. Disposal of anthrax carcasses correctly
6. Avoid direct contact with an infected animal
Complications of Anthrax
The most serious complications of anthrax –
1. Inflammation of the membranes and fluid covering the brain and spinal cord, leading to hemorrhagic meningitis (massive bleeding) and damage to multiple organ systems (sepsis) and death.
Anthrax Questions and Answers
1. What is anthrax?
Anthrax is an soil-borne infectious disease caused by the spore-forming bacterium Bacillus anthracis. It causes dark, coal-like structure on affected areas.
2. What are causative agent of Anthrax and Plague?
The causative agent of Anthrax bacterium Bacillus anthracis and The causative agent of Plague bacterium, bacillus Yersinia pestis.
3. How is anthrax transmitted?
Human get infected breathing in spores or ingesting food or drinking water that contaminated with spores or enter spores in a cut, wound, or scrape in the skin.
4. What are the clinical manifestation of anthrax disease?
The clinical sign depend upon the type of anthrax infection. The most common symptoms are – Fever and chills, muscle pain, Diaphoresis, Cyanosis, Sore throat, Painful swallowing, Acute Abdominal pain, Macular and papular skin lesions, Painless black eschar, Painful lymphadenopathy.
5. What are types of Anthrax infection?
The development of anthrax illness depend upon how Bacillus anthracis enters into the human body. In humans, there are three types of anthrax infection occurs –
1. Inhalation anthrax
2. Gastrointestinal anthrax
3. Cutaneous anthrax
