Anthrax

Anthrax

Article
Healthy Lungs
Diseases & Conditions
+1
Contributed byMaulik P. Purohit MD MPHApr 04, 2018

What are the other Names for this Condition? (Also known as/Synonyms)

  • Cutaneous Anthrax
  • Gastrointestinal Anthrax
  • Inhalational Anthrax

What is Anthrax? (Definition/Background Information)

  • Anthrax is an infectious disease caused by the bacterium Bacillus anthracis
  • These bacteria can be found in dormant spore forms that can survive for hundreds of years in the soil, and then grow to form bacteria that cause infections, when conditions are favorable
  • Anthrax is typically a disease of animals (essentially wild/domestic herbivores, animals that graze), but humans may get the disease in the following manner:
    • If they are in close contact with the animals
    • Through biological laboratories, during work involving the microorganism
    • In rare cases, due to an intentional exposure

There are 3 types of Anthrax:

  • Skin (Cutaneous Anthrax)
  • Lungs (Inhalational Anthrax)
  • Digestive (Gastrointestinal Anthrax)

Who gets Anthrax? (Age and Sex Distribution)

Anthrax infections are very uncommon. They are typically associated with occupational hazards, but not any particular age or sex distribution.

What are the Risk Factors for Anthrax? (Predisposing Factors)

Risk factors for Anthrax include:

  • Working with animal products like wool and hides (animal skin)
  • Individuals in the military, who may be deployed to an area with high risk of exposure
  • Working with Anthrax in a research laboratory
  • Handling or dressing animals in an agricultural-or hunting-setting

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases ones chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Anthrax? (Etiology)

Anthrax can enter the human body through the intestines (ingestion), lungs (inhalation), or skin (cutaneous). It causes distinct clinical symptoms, based on its site of entry.The form of Anthrax that causes infection is the spore-form. In order to develop any of the 3 forms of Anthrax, one must be exposed to a relatively large number of spores.

Animal exposure:

  • Bacillus anthracis is naturally found in the soil and therefore, may be associated with grazing animals, such as sheep and cows
  • The most common way that humans get infected by Bacillus anthracis and develop Anthrax is by handling animal-products, such as wool or hides
  • Cutaneous Anthrax infection is the most common form and is seen in people working on farms or working in industries that process cow hides and wool
  • Occasionally, individuals may get Inhalational Anthrax, by working with animal products
  • Individuals may also develop Gastrointestinal Anthrax, by eating undercooked meat from infected animals

Research laboratory:

  • Certain researchers are allowed to handle the microorganism in special bio safety level 3 laboratories. These individuals work with the organism to understand its physiology, and how to design therapeutics or antibiotics, which are used to treat patients who develop Anthrax
  • Historically, there have been several cases of Inhalational and Cutaneous Anthrax that have developed from accidental exposure in the laboratory setting

Anthrax as a bioweapon:

  • Anthrax has been used as a biological weapon to intentionally cause infection in humans

It is extremely important to note that Anthrax has not been shown to spread from one person to another.

What are the Signs and Symptoms of Anthrax?

The 3 different forms of Anthrax have differing signs and symptoms:

Cutaneous:

  • The skin disease usually begins as a small, painless, itchy spot that quickly develops into a blister
  • When the blister erodes, it leaves a painless black ulcer called an “eschar”. The surrounding skin may become swollen and puffy
  • Lymph nodes near to the ulcer may become enlarged

Gastrointestinal:

  • Nausea
  • Vomiting
  • Loss of appetite
  • Fever
  • The condition may progress to include abdominal pain, vomiting of blood, and severe diarrhea

Inhalational: There are generally two different phases of the disease.

  • The first phase includes symptoms that are not specific to Anthrax and typically involve muscle soreness, fever, chills, sweats, and weakness. Other symptoms may include nausea, vomiting of blood, and shortness of breath, and/or chest pain
  • The second phase often develops suddenly and symptoms include fever, severe shortness of breath, and shock

How is Anthrax Diagnosed?

Apart from a physical exam and evaluation of medical history, a diagnosis of Anthrax would involve:

  • Cutaneous Anthrax: The physician may obtain a small sample of skin around the area of ulceration and send it to a laboratory, in order to examine it under the microscope and grow a culture of the Anthrax bacteria
  • Inhalational Anthrax: The physician may order a chest x-ray to look for signs of infection. They may also take blood samples to study under the microscope, and/or for culture tests, to look for the Anthrax bacteria. The physician may obtain samples of fluid from the spine, to look for signs of any infection
  • Gastrointestinal Anthrax: Using a flexible scope, called an endoscope, the physician may study the throat or intestines for signs of infection. Stool samples may also be taken, to look for the organism

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Anthrax?

Complications of Anthrax infection depend on the type of infection.

  • If the bacteria enter into the bloodstream, which is common with Inhalational Anthrax, the patient may develop a septic shock
  • Another complication, if bacteria enter the blood is that they can cross the blood-brain barrier and cause infection in the nervous system

How is Anthrax Treated?

  • The most successful treatment for Anthrax infection is antibiotics; this treatment is effective for all three types of Anthrax
  • The response to treatment is highly dependent on how early in the disease stage, the treatment is started. Therefore, it is very important to identify Anthrax infections, as early as possible

Generally, there are two different categories for treatment:

  • If an individual is known to be exposed to Anthrax, but does not yet have any symptoms of disease
  • If an individual has signs and symptoms of disease

To prevent disease after exposure, patients usually receive antibiotics (such as ciprofloxacin, levofloxacin, doxycycline, or penicillin) combined with Anthrax vaccine to prevent an infection.

  • In the event of an outbreak in the community - friends, family, or co-workers of patients, who develop Anthrax, may also be treated to limit their chance of developing the disease
  • To treat individuals, who have signs of the disease; patients typically receive a 60-day course of antibiotics. Success depends on the type of Anthrax and how soon treatment began

How can Anthrax be Prevented?

The only known method to prevent Anthrax is through vaccination. Currently, the vaccine is not available for general public use, but is available for individuals with high risk of exposure, such as:

  • Certain army personnel
  • Those who work in research laboratories with the organism
  • Individuals entering contaminated regions/zones

As indicated above, those who have been exposed to the spores, but have not yet developed the disease, may also receive the vaccine.

What is the Prognosis of Anthrax? (Outcomes/Resolutions)

  • The prognosis depends upon the type of Anthrax infection
  • If treated with antibiotics, almost all individuals with Cutaneous Anthrax survive. Even in those cases of Cutaneous Anthrax that are not treated with antibiotics, 80% of the patients survive
  • Gastrointestinal Anthrax is a more serious form of infection; about 25-50% of the individuals infected with Gastrointestinal Anthrax may die
  • Inhalational Anthrax is the most severe form of Anthrax. Historically, 92% of those infected by Inhalational Anthrax do not survive. However, these figures may be changing with new developments in medicine

In the 2001 US letter mailings incident; with the use of antibiotics on individuals, who developed Inhalational Anthrax, only 45% died.

Additional and Relevant Useful Information for Anthrax:

In 2001 in the United States, highly purified Anthrax spores were placed in envelopes and mailed anonymously through the postal system. Most of the individuals, who developed the infection, were postal workers. They developed Cutaneous Anthrax by handling contaminated mail, or Inhalational Anthrax by breathing in spores released into the air, after being processed through the mail sorting machines. There were 22 cases in total; 11 cases of Inhalational Anthrax, and 11 cases of Cutaneous Anthrax.

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Maulik P. Purohit MD MPH picture
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Maulik P. Purohit MD MPH

Assistant Medical Director, Medical Editorial Board, DoveMed Team

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