Introduction:
Bacillus anthracis, a rod-shaped, gram-positive bacterium, holds a notorious reputation as the causative agent of anthrax, a potentially fatal disease affecting both humans and animals. While rare in developed countries, understanding this resilient microbe is crucial for ensuring public health and biosecurity.
Unveiling Bacillus anthracis: The Bacterium Behind Anthrax
Bacillus anthracis, a rod-shaped, gram-positive bacterium, holds a notorious reputation as the causative agent of anthrax, a potentially fatal disease affecting both humans and animals. While rare in developed countries, understanding this resilient microbe is crucial for ensuring public health and biosecurity.
A Spore-Forming Survivor:
Unlike most bacteria, Bacillus anthracis possesses the unique ability to form endospores. These dormant structures are remarkably tough, allowing the bacteria to survive harsh environmental conditions like extreme temperatures, desiccation (drying out), and even exposure to disinfectants. Spores can persist in soil for decades, posing a long-term threat in contaminated environments.
Life Cycle and Threat Potential:
Bacillus anthracis primarily resides in the soil, particularly in regions where infected animals have died or their remains have been improperly disposed of. Herbivores like sheep, goats, and cattle are highly susceptible to anthrax through ingestion of contaminated soil or water. Once infected, animals can become sick rapidly and die within a few days. Their carcasses, if not handled properly, release spores back into the environment, perpetuating the cycle of contamination.
Humans can contract anthrax through various routes:
- Cutaneous anthrax: The most common form, contracted through direct contact with infected animal tissues or spores. It manifests as a painless, black eschar (skin sore) at the site of infection.
- Inhalation anthrax: The most severe form, inhaled spores lodge in the lungs, causing flu-like symptoms that progress rapidly to respiratory failure.
- Gastrointestinal anthrax: Ingestion of contaminated food or water leads to nausea, vomiting, and severe abdominal pain.
Describe the Bacillus anthracis: (anthrax)?
Anthrax (pronounced “AN-thraks”) is an infectious disease caused by exposure to Bacillus anthracis bacteria. The bacteria are dormant, or inactive, in soil. Disease from anthrax mostly affects animals that graze on land that has the bacteria and is extremely rare in the United States.
People can become infected through inhaled bacteria spores, contaminated food or water, or skin wounds. Antibiotics are the first line of treatment for this potentially deadly infection. There are other treatments, including a vaccine.
Types of Bacillus anthracis:
The types of Bacillus anthracis reflect the different ways the bacteria enter your body. Anthrax types include:
- Cutaneous (skin): Bacteria infect your body through a wound in your skin. Cutaneous anthrax is the most common and least deadly form. Veterinarians and people who handle animal wool, hides or hair are at the highest risk.
- Gastrointestinal: This type affects people who eat undercooked or raw meat from an infected animal. The bacteria affect your esophagus, throat, stomach and intestines. Gastrointestinal anthrax is rare in the United States. U.S.-based producers vaccinate livestock against anthrax and identify sick animals before slaughter.
- Inhalation: People who breathe in anthrax spores can develop this deadly form of anthrax. It can cause severe breathing problems and death. Inhalation anthrax is sometimes called woolsorter’s disease because people who work in wool mills — as well as slaughterhouse and tannery workers — may inhale spores from infected animals.
- Injection: People who inject heroin can get injection anthrax. This type is more common in northern Europe and hasn’t been reported in the United States. Injection anthrax causes infection deep under your skin or in muscle.
How common is anthrax?
Anthrax is found all over the world, although the disease is extremely rare in the United States. Disease outbreaks tend to occur in developing countries that don’t vaccinate livestock against the infection. These areas include:
- Caribbean islands.
- Central America.
- Central and Southwest Asia.
- South America.
- Southern and Eastern Europe.
- Sub-Saharan Africa.
Is Bacillus anthracis a biological weapon?
A bioterrorism anthrax attack using anthrax spores is a possibility. In 2001, a U.S. military researcher mailed envelopes containing anthrax powder to members of Congress and the media. Five of the 22 people who developed cutaneous or inhalation anthrax died. Federal agencies continue to work to prevent future anthrax attacks.
Symptoms and Causes
What are the symptoms of anthrax?
Bacillus anthracis symptoms vary depending on the type. Symptoms typically appear within one week of exposure. Sometimes, signs of inhalation anthrax aren’t noticeable for two months. Depending on the type, symptoms include:
- Chest pain and trouble breathing.
- Fatigue.
- Fever and profuse sweating.
- Headache or muscle aches.
- Itchy blisters or bumps.
- Skin ulcer (sore) with a black center.
- Nausea and vomiting, abdominal pain and bloody diarrhea.
- Swollen lymph nodes.
What causes anthrax?
Bacillus anthracis bacteria cause anthrax. The bacteria produce spores that can live in the ground for years. Wild animals like deer, and livestock such as cattle or sheep, can inhale or ingest the dormant (inactive) spores while grazing.
After mixing with bodily fluids, anthrax bacteria activate, multiply and spread throughout your body. The bacteria cause a toxic, potentially deadly reaction. The same process happens to people who inhale, ingest or come into skin contact with the spores.
Is anthrax contagious?
Anthrax isn’t contagious like chickenpox or the flu. You can’t catch anthrax from being around someone who’s infected. Rarely, people develop cutaneous anthrax after coming into direct contact with another person’s infected skin lesion.
Who might get Bacillus anthracis?
Certain people are more at risk for exposure to anthrax, including:
- Farmers and livestock handlers.
- Military members and travelers to countries known to have problems with anthrax.
- Researchers and laboratory workers who study the bacteria.
- Veterinarians who work with infected livestock.
- Wool mill, tannery and slaughterhouse workers.
- Drum makers who use animal hides.
- Heroin users.
What are the complications of Bacillus anthracis?
Untreated Bacillus anthracis can be deadly. Complications vary depending on the anthrax type:
- Cutaneous: Almost everyone who gets treated for cutaneous anthrax survives. About 20% of infected people who don’t get treatment die.
- Gastrointestinal: Approximately 60% of treated people survive. Without treatment, more than half of infected people die. Gastrointestinal anthrax can cause deadly brain and spinal cord swelling (meningoencephalitis).
- Inhalation: About 55% of infected people who receive treatment survive. That number drops to about 15% for people who aren’t treated.
Diagnosis and Tests
How is anthrax diagnosed?
Depending on your symptoms and the anthrax type, your healthcare provider may conduct one or more of these tests:
- Biopsy of skin lesion.
- Blood tests.
- Chest X-ray.
- Computed tomography (CT) scan.
- Lab tests on poop (stool) or mucus.
- Lumbar puncture (spinal tap).
Management and Treatment
What is the treatment for anthrax?
Most forms of anthrax respond well to treatment. If you think you’ve been exposed, call your healthcare provider immediately. Fast treatment with antibiotics can stop the infection from developing. Anthrax treatments include:
- Antibiotics: Oral, injectable or intravenous (through your vein) antibiotics fight infection. You may need antibiotics for 60 days. Commonly used antibiotics include ciprofloxacin (Cipro®) and doxycycline (Doryx®).
- Antitoxins: These injectable antibody medications neutralize anthrax toxins in your body. Treatment typically includes antibiotics, too.
- Vaccine: A vaccine to prevent anthrax infection, BioThrax®, also treats infected people. Treatment involves three doses of the vaccine over four weeks. You’ll receive antibiotics at the same time.
Prevention
How can I prevent anthrax?
The anthrax vaccine is 90% effective at preventing infection. The vaccine is only available to people between the ages of 18 and 65 who work in high-risk professions, such as farmers and livestock handlers, military members, researchers who study the bacteria, veterinarians and others as listed above. You receive five doses of the vaccine over 18 months. Afterward, you’ll need an annual booster shot. The vaccine also stops infection if you’ve knowingly been exposed to anthrax. In the United States, livestock that graze in anthrax-prone areas, such as certain parts of Texas, receive a different anthrax vaccine made for animals.
The anthrax vaccine isn’t available to the general public. If you’re traveling to an area known to have anthrax problems, you shouldn’t:
- Eat raw or undercooked meat.
- Handle or buy souvenirs made with animal hide or hair.
- Pet or touch animals.
Outlook / Prognosis
What is the outlook (prognosis) for people with anthrax?
If you think you’ve been exposed to anthrax, call your healthcare provider to start antibiotics or other therapies immediately. Untreated anthrax can be deadly. Fast treatment can prevent severe infection and life-threatening symptoms, improving your odds of a full recovery.
When should I see my healthcare provider?
You should call your healthcare provider if you suspect you’ve been exposed to anthrax and you experience:
- Blood in respiratory secretions (coughing up blood).
- Blood in vomit or stool.
- Chest pain.
- Difficulty breathing.
- Diarrhea.
- Fever.
- Severe abdominal pain.
