What is Anthrax?
Anthrax is caused by the bacterium, Bacillus anthracis. This bacterium is tiny, functions in the presence or absence of oxygen, and is generally classified as advantageous or fluctuating in appearance under a microscope. The bacterium also forms spores – like hard shells that protect it. Bacillus anthracis creates toxins that play a significant part in making the disease harm the body and grow well on blood-containing mediums where they form large, irregular colonies. The name ‘anthrax’ is derived from the Greek word ‘anthrakis,’ which means black – referencing the black, dead tissue that’s seen in skin-based anthrax.
Though Bacillus anthracis is generally found throughout nature and is stable in its environment, it’s also known to be a possible source of a biological weapon.
Anthrax can affect the skin or internal organs and is almost always fatal when breathed in. Symptoms usually show up several days after being infected, making this bacterium difficult to trace.
What Causes Anthrax?
Bacillus anthracis, the bacteria that causes anthrax, is extremely durable when in a spore state. It can contaminate soil all over the world. These spores can stay dormant and alive in the environment for many years. Anthrax commonly affects animals like sheep, goats, cows, deer, and antelope, especially in the summer and fall. It’s most commonly seen in animals who graze.
People can get anthrax from contact with infected animals. This can happen when butchering animals, handling their hides, or eating their meat if it’s raw or undercooked. If the spores touch your skin, it causes a type of anthrax that affects the skin. If you breathe in the spores or eat them, it can lead to anthrax in the lungs or stomach.
It’s important to note that anthrax is usually gotten from animals. There are no known cases where one person passed anthrax directly to another person.
Risk Factors and Frequency for Anthrax
Anthrax is a disease that can be found all over the world, with the World Health Organization estimating that there are between 2,000 to 20,000 cases globally each year. However, it’s not very common in the United States. But there was an outbreak in North Dakota in 2000. The disease can occur in different forms depending on how people come into contact with it. If it’s through the skin, it causes cutaneous anthrax. If someone inhales or swallows the spores, it leads to inhalational, pharyngeal, or GI anthrax.
The Centers for Disease Control and Prevention has marked anthrax as a category A priority pathogen. This means it could potentially be spread as a biological weapon.
Signs and Symptoms of Anthrax
Inhalational anthrax typically develops 1 to 6 days after exposure, starting with general symptoms like fever, nausea, vomiting, chest discomfort, and a dry cough. As the bacteria multiply in the lymph nodes in the chest, this leads to more severe symptoms including breathing problems, airway blockage due to swollen lymph nodes, and even respiratory failure and shock. Half of the people with inhalational anthrax may also develop meningitis, with symptoms like headache, confusion, and eventually coma. A chest X-ray for these patients typically shows a widened area in the middle of the chest due to significantly swollen lymph nodes. Some patients might also show signs of fluid in their lungs or hemorrhage. The disease can progress rapidly, and patients may die within 1 to 10 days from symptom onset.
Gastrointestinal (GI) anthrax results from eating contaminated, undercooked meat or accidentally swallowing inhaled spores. Depending on where the infection is located, a patient might have throat or intestinal symptoms. Throat anthrax causes ulcers in the back of the throat, difficulty swallowing, neck swelling, and swollen lymph nodes. Intestinal anthrax causes fever, nausea, vomiting, and diarrhea. The symptoms may further worsen with bloody diarrhea and vomiting blood. More often than not, the lower part of the small intestine and the beginning of the large intestine are involved. If left untreated, the disease can cause high levels of bacteria in the blood. The death rate varies from 25% to 60%.
Skin anthrax typically appears 1 to 10 days after contact with the bacteria, starting as an itchy bump that turns into a painless ulcer over several days. This ulcer may have small blisters around it and will have a black, necrotic center with swelling that doesn’t dent when you press on it. The lack of pain is a distinct characteristic of skin anthrax, differentiating it from other conditions. As the ulcer heals, the blackened skin flakes off after 1 to 2 weeks. Without proper treatment, the death rate can reach about 20%.
Injection anthrax occurs when a person uses needles that are contaminated with anthrax. It starts as a group of small blisters or bumps at the injection site, which then develop into painless ulcers like those seen in skin anthrax. It could be more difficult to recognize and it can spread to the entire body more quickly than skin anthrax.
Testing for Anthrax
If you’re suspected of being exposed to anthrax, the CDC recommends certain tests and exams to confirm the diagnosis. Based on your symptoms, you may need different tests including PCR (a genetic test), gram stain (a type of bacteria test), and various cultures from your blood, lung fluid, any ulcers, spinal fluid and stool. Routine tests like a complete blood count (CBC) and chest x-ray might also be necessary. Depending on your situation, testing for other disease-causing agents might be included as well.[7][8]
It is important that lab staff are informed that they may be handling anthrax in your samples to ensure their safety. Cutaneous anthrax (which affects the skin) can be diagnosed with a stain that makes the anthrax bacteria visible under a microscope.
For patients with inhalational anthrax (which affects the lungs), a chest x-ray might show an enlarged area in the chest called the mediastinum. A CT scan might show additional changes like swollen lymph nodes in the chest, bleeding in the mediastinum, and fluid build-up in the pleural space (the area around the lungs).
Treatment Options for Anthrax
Any case of inhaled anthrax is considered a potential act of war fare , meaning safety precautions must be taken. Healthcare workers should protect themselves by wearing gloves, masks and splash protection gear.
If an individual comes into contact with anthrax, they should immediately wash their hands with soap and water and put their clothes in a plastic bag for examination. It’s vital to notify your local health authorities and the Center for Disease Control (CDC) as soon as possible because anthrax is a dangerous infection that needs to be reported.
The CDC provides detailed treatment guidelines for anthrax based on how the disease appears in patients. These even include alternatives for certain patients.
Generally, treatment for inhaled anthrax involves a combination of multiple drugs: one that kills the bacteria and one that stops the bacteria from making proteins. Preferred medicines include intravenous ciprofloxacin with either clindamycin or linezolid. If the patient has a brain infection (meningitis) caused by anthrax, it’s recommended to use an even more comprehensive combination of drugs.
For a skin Anthrax infection, oral ciprofloxacin or doxycycline are usually effective. However, if the skin infection causes extensive swelling or is around the head and neck region, multiple intravenous drugs are recommended.
In addition to antibiotics, doctors might also recommend a therapy using antitoxins, which are substances that counteract the toxins produced by the anthrax bacteria. Several types of these antitoxin products have been developed.
Vaccines against anthrax are available for both humans and animals. These greatly reduce, but do not completely eliminate, the risk of anthrax infections. Anthrax vaccinations are not recommended for the average person in the U.S, but could be necessary for high-risk individuals, like certain veterinarians, laboratory workers and some members of the military who come into contact with animal hides or fur. The vaccine might be widely recommended to a community in response to an anthrax bio-warfare event.
Healthcare professionals have developed a set of guidelines for people exposed to anthrax even after an event has ended:
- Anyone who has inhaled anthrax should be treated for 60 days, no matter their vaccination status.
- Several medicines should be used together for the most effective treatment.
- Antibiotics like quinolones, doxycycline and ciprofloxacin are approved for treating inhaled anthrax.
- If anthrax causes a brain infection, it should be treated with three different antibiotics.
- For skin anthrax, treatment typically involves doxycycline or a quinolone.
- Treatments for pregnant women and new mothers are the same as those for non-pregnant individuals.
What else can Anthrax be?
When a doctor is trying to diagnose inhalation anthrax, they have to make sure it’s not actually another disease that has similar symptoms. These could include things like:
- Commonly acquired pneumonia
- The flu
- Respiratory syncytial virus (a common virus that can cause cold-like symptoms)
- Pneumonic plague (a type of plague that specifically affects the lungs)
- Tularemia (a disease caused by bacteria that can be caught from animals)
If a person has a skin complaint and the doctor is thinking it might be skin anthrax, they need to also consider whether it might be due to:
- A skin abscess (a painful, pus-filled lump beneath the skin) caused by a staphylococcal bacteria
- Cat scratch disease (a bacterial infection that can be caught from the scratch or bite of a cat)
- Tularemia
- A spider bite
- Ecthyma gangrenosum (a severe skin infection often due to a kind of bacteria called Pseudomonas aeruginosa)
When considering a gastrointestinal anthrax diagnosis, doctors also have to exclude ulceroglandular tularemia or bubonic plague. Ulceroglandular tularemia is the most common type of tularemia and comes with skin ulcers. Bubonic plague is a dangerous and often deadly disease caused by bacteria and spread by fleas.
What to expect with Anthrax
Most anthrax cases affect the skin and typically get better with or without treatment. If caught early and treated with antibiotics, the death rate is under 2%. But inhaled anthrax is very dangerous and often leads to poor outcomes. Despite getting appropriate treatment, close to half of the people with this form of anthrax have been known to die.
Preventing Anthrax
If you’ve been exposed to a certain infection, it’s recommended to take a type of antibiotic, either a quinolone or doxycycline, for at least 4 weeks. This is called post-exposure prophylaxis.
If there’s a chance you might have inhaled the infection, there are special medications called oblitoxaximab and raxibacumab that are often suggested. These are specific types of agents called monoclonal antibodies. They are usually used in conjunction with the antibiotics.
For long-term protection, there’s a vaccine you can take. It’s given in 3 separate doses over the course of a 4 week period.