Anthrax Causes, Symptoms, Diagnosis, Treatment, Prevention, Vaccine

Anthrax Causes, Symptoms, Diagnosis, Treatment, Prevention, Vaccine

What is anthrax?

Anthrax is a serious illness caused by a spore-forming bacterium, Bacillus anthracis. Although anthrax affects mainly livestock and wild game (such as cattle, sheep, pigs, horses, goats, camels, and antelopes), humans can become infected through direct or indirect contact with sick animals. Normally, anthrax isn't transmitted from person to person, but in rare cases, anthrax skin lesions may be contagious.

Most often, anthrax bacteria enter your body through a wound in your skin. You can also become infected by eating contaminated meat or inhaling the spores. Signs and symptoms, which depend on the way you're infected, can range from skin sores to nausea and vomiting or shock.

Anthrax can be found worldwide, but it is much more common in developing countries or countries without veterinary public health programs, including South and Central America, Southern and Eastern Europe, Asia, Africa, the Caribbean, and the Middle East.

Prompt treatment with antibiotics can cure most anthrax infections contracted through the skin or contaminated meat. Inhaled anthrax is more difficult to treat and can be fatal.

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Why was anthrax prominent in the news?

Anthrax was prominent in the news because anthrax spores have been used in intentional acts of bioterrorism in the United States shortly after 9/11/01. Even a very tiny amount of anthrax spores can be aerosolized and inhaled by humans and result in morbidity and mortality. However, is highly unlikely that you or someone you know will contract anthrax. Aside from the people who contracted anthrax from spores delivered through the US mail in bioterrorist acts, there have been few cases of anthrax infection reported in the United States. Most were associated with handling infected animals or animal products.

What causes anthrax?

Anthrax commonly affects hoofed animals such as sheep, cattle, and goats. Humans who come into contact with infected animals can get sick with anthrax as well.

There are three main routes of anthrax infection:

Cutaneous anthrax occurs when anthrax spores touch a cut or scrape on the skin.

  • It is the most common type of anthrax infection.
  • The main risk is contact with animal hides or hair, bone products, and wool, or with infected animals. People most at risk for cutaneous anthrax include farm workers, veterinarians, and tannery and wool workers.
Inhalation anthrax develops when anthrax spores enter the lungs through the respiratory tract. It is most commonly contracted when workers breathe in airborne anthrax spores during processes such as tanning hides and processing wool.

Breathing in spores means a person has been exposed to anthrax, but it does not mean the person will have symptoms.

  • The bacteria spores must germinate or sprout (the same way a seed might sprout before a plant grows) before the actual disease occurs. The process usually takes 1 to 6 days.
  • Once the spores germinate, they release several toxic substances. These substances cause internal bleeding, swelling, and tissue death.
Gastrointestinal anthrax occurs when someone eats anthrax-tainted meat.

What are the symptoms of anthrax?

There are three types of anthrax infections in humans.

Cutaneous (skin-derived) anthrax

Cutaneous anthrax accounts for 95 percent of anthrax cases and occurs when the bacterium enters a cut or abrasion on the skin. Typically, the infection occurs through handling the wool, hide, leather, or hair of animals infected with anthrax. The anthrax skin infection in humans begins as a raised itchy bump that resembles an insect bite. Then, 1 to 2 days later, the bump develops into a painless lesion or ulcer with a characteristic black area in the center. The lymph glands in nearby area may swell. If left untreated, about 20 percent of individuals with cutaneous anthrax die. However, deaths are rare with appropriate antimicrobial therapy.

Intestinal anthrax

Intestinal anthrax occurs after eating contaminated meat and results in an acute inflammation of the small intestinal tract. This is very uncommon in the United States. Initial symptoms include nausea, loss of appetite, and fever followed by abdominal pain, vomiting of blood, and severe diarrhea. Death occurs in 25 percent to 60 percent of individuals infected with intestinal anthrax.

Inhalational anthrax

Inhalational anthrax is extremely rare but can occur if someone breathes anthrax spores, which are kicked up into the air by mail sorting machines or released through a bioterrorist act. The anthrax spores are inhaled into the lungs. The initial symptoms may be nonspecific cold, sore throat, or flu (without the muscle aches) symptoms, but after a few days, the symptoms may progress to severe breathing problems and shock and spread into the central nervous system.. Inhalation anthrax is often fatal without early recognition and treatment.

It usually takes less than 7 days for symptoms of skin and intestinal anthrax to appear. However, symptoms can appear as early as 48 hours after the lungs have been exposed to anthrax spores.

When to Contact a Medical Professional

Call your health care provider if you have been exposed to anthrax, or if you develop symptoms of any type of anthrax.

How common is anthrax?

Anthrax is now rare in humans in the United States and developed countries. It still occurs today, largely in countries lacking public-health regulations that prevent exposure to infected goats, cattle, sheep, and horses and their products. In the last few years, there have been rare cases of anthrax in people exposed to imported animal hides used to make drums. Drum players, drum makers, and their family members have been infected in this way. The major concern for those of us in western countries (who don't play drums) is the use of anthrax as an agent of biological warfare.

How long is the incubation period with anthrax?

The incubation period (the period between contact with anthrax and the start of symptoms) may be relatively short, from one to five days. Like other infectious diseases, the incubation period for anthrax is quite variable and it may be weeks before an infected individual feels sick.

How is anthrax diagnosed?

Your doctor will first want to rule out other, more common conditions that may be causing your signs and symptoms, such as flu (influenza) or pneumonia. You may have a rapid flu test to quickly diagnose a case of influenza. If other tests are negative, you may have further tests to look specifically for anthrax, such as:

Skin testing

A sample of fluid from a suspicious lesion on your skin or a small tissue sample (biopsy) may be tested in a lab for signs of cutaneous anthrax.

Blood tests

You may have a small amount of blood drawn that's checked in a lab for anthrax bacteria.

Chest X-ray or computerized tomography (CT) scan

Your doctor may request a chest X-ray or CT scan to help diagnose inhalation anthrax.

Endoscopy and stool samples

To diagnose intestinal anthrax, your doctor may examine your throat or intestine with an endoscope — a thin, flexible tube with a tiny camera at its tip. In some cases, a sample of your stool may be checked for anthrax bacteria.

Spinal tap (lumbar puncture)

In this test, your doctor inserts a needle into your spinal canal and withdraws a small amount of fluid. A spinal tap is usually done only to confirm a diagnosis of anthrax meningitis.

How is anthrax infection treated?

Antibiotics are usually used to treat anthrax. Antibiotics that may be prescribed include penicillin, doxycycline, and ciprofloxacin.

Inhalational anthrax is treated with a combination of antibiotics such as ciprofloxacin plus another medicine, which are given by IV (intravenously). Antibiotics are usually taken for 60 days by people who have been exposed to anthrax, because it can take spores that long to germinate.

Cutaneous (skin) anthrax is treated with antibiotics taken by mouth, usually for 7 to 10 days. Doxycycline and ciproflaxin are most often used.

How can anthrax be prevented?

Antibiotics are recommended to prevent infection in anyone exposed to the spores. Ciprofloxacin, doxycycline and levofloxacin (Levaquin) are approved by the Food and Drug Administration for post-exposure prevention of anthrax in adults and children.

Anthrax vaccine 

An anthrax vaccine for humans is available, but it's not 100 percent effective. The vaccine doesn't contain live bacteria and can't lead to infection, but it can cause side effects, ranging from soreness at the injection site to more-serious allergic reactions. The vaccine isn't recommended for children, pregnant women or older adults.

The vaccine isn't intended for the general public. Instead, it's reserved for military personnel, scientists working with anthrax and people in other high-risk professions.

Avoiding infected animals 

If you live or travel in a country where anthrax is common and herd animals aren't routinely vaccinated, avoid contact with livestock and animal skins as much as possible. Also avoid eating meat that hasn't been properly cooked.

Even in developed countries, it's important to handle any dead animal with care and to take precautions when working with or processing imported hides, fur or wool.

Who should receive the anthrax vaccine?

The vaccine is currently recommended for use by those at most risk for occupational exposure to the bacteria such as:

  • military personnel (due to exposure as a biological warfare weapon)
  • laboratory workers
  • livestock handlers
  • veterinarians
  • people who work with animal hides or furs imported from areas of the world where the disease is common
  • people who handle potentially infected animal products from areas where the disease is common

Will the anthrax vaccine become more widely available to the public?

Health officials currently do not recommend the vaccine for general use by the public because of the rarity of anthrax infection. In addition, the vaccine can’t be practically given in response to a bioterrorism act due to its prolonged administration schedule – the vaccine is given as six subcutaneous injections over the course of 18 months. If diagnosed early, anthrax can be successfully treated with antibiotics. Researchers are working to develop a second generation anthrax vaccine as well as other treatment options to protect the public in the event of a bioterrorism attack.

Outlook (Prognosis)

When treated with antibiotics, cutaneous anthrax is likely to get better. However, up to 20% of people who do not get treatment may die if anthrax spreads to the blood.

People with second-stage inhalation anthrax have a poor outlook, even with antibiotic therapy. Up to 90% of cases in the second stage are fatal.

Gastrointestinal anthrax infection can spread to the bloodstream, and may result in death.