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Anthrax

Overview

Anthrax is a serious bacterial infection caused by a spore-forming bacterium known as Bacillus anthracis. It is a rare disease and usually affects livestock and wild animals, but human beings can also catch this infection. The symptoms of this infection may vary depending on how you got infected. If the symptoms of this infection are not addressed immediately, it may prove to be fatal in a short period. Treatment can be done by the use of wide-spectrum antibiotics and antitoxins. 

Causes

The causative agent of anthrax is Bacillus anthracis, a gram-positive, spore-forming bacteria. The spores produced by this bacterium are the primary source of infection. These spores are present naturally in soil across most regions of the world. They can remain in a dormant state for many years until they find a host. Normally these spores affect domestic livestock such as sheep, cattle, goats, etc., and other wild animals. But this infection can infect humans by contacting infected animals, soil, or contaminated surfaces. In some cases, anthrax can also occur due to injection of heroin. 

Types

Depending on how the bacteria enters your body, anthrax can be divided into four types: cutaneous, gastrointestinal, inhalation and injection.

Cutaneous anthrax is the most common type of anthrax. In this type, the bacteria enters the body through a cut or wound on your skin. Farmers, veterinarians, and other people who are in direct contact with infected animals are at risk of getting cutaneous anthrax. It is the least deadly type among others.

Gastrointestinal anthrax occurs when you eat undercooked or raw meat of an infected animal. The bacteria enter your system via the gastrointestinal tract and can affect your digestive organs. It is a rare type.

Inhalation anthrax results from inhaling the spores produced by Bacillus anthracis. It is a potentially fatal form of anthrax that can affect your respiratory system. People who live close to infected animals or farms are at risk of contracting this infection.

 

Injection anthrax is less common and can result from the injection of illegal drugs such as heroin. It can also lead to severe symptoms, including meningitis, if not addressed early. 

Risk Factors And Epidemiology

The risk of anthrax is higher for certain groups of people. Military members can be at risk if they are deployed to regions with active cases of anthrax. Travelers may also get infected the same way. People who work with livestock or farm animals are at high risk of contracting this infection. Even those who handle wool, fur, or skins of dead animals may also get this infection. Veterinarians, farmers, slaughterhouse workers, researchers, and laboratory workers who study the animals or bacteria are at risk. Injection of illegal drugs may also put you at risk of this condition.

 

The incidence of anthrax in the United States is low. The highest number of cases have been seen in Africa, Central Asia, and Southern Asia. Cases of injection anthrax have only been noticed in Europe. This bacteria can cause infection in any person regardless of age or gender.

Signs And Symptoms

The signs and symptoms of each type of anthrax may vary. In majority of the cases, symptoms take six days to appear. The most common type is cutaneous anthrax which presents with a raised, itchy bump. This lesion quickly develops into a sore with a black-colored center. The nearby glands appear swollen, and you may also develop flu-like symptoms. The symptoms of gastrointestinal anthrax are more severe, including nausea/vomiting, abdominal pain, fever, loss of appetite, swollen neck, sore throat, and bloody diarrhea.

 

Inhalation anthrax has the most fatal course, and its symptoms include chest discomfort, fever, sore throat, shortness of breath, bloody cough, and difficulty breathing. The affected person may develop meningitis or shock in later stages. Injection anthrax presents with swelling and redness at the site of injection, followed by shock and multiple organ failure. 

Diagnosis

Your doctor will ask for occupational and other medical history to find a possible cause. A rapid flu test may be suggested to rule out influenza. If any other common illnesses are not present, further tests are required to diagnose anthrax. A sample from skin lesion can be taken to look for cutaneous anthrax if present. Blood culture tests and stool tests are also done to look for anthrax bacteria. If your doctor suspects a severe form of anthrax that may have caused meningitis, lumbar puncture is done to take a sample of your spinal fluid which is tested for anthrax bacteria. Additional tests such as CT scans and MRI can be done to visualize damage done to the respiratory tract. 

Differential Diagnosis

Because anthrax has different routes of infection that present with different symptoms, it needs to be differentiated from other diseases that may cause similar issues. For example, inhalation anthrax needs to be differentiated from influenza, diphtheria, pharyngitis, Ludwig’s angina etc. Each type needs to be ruled out for other common causes. 

Treatment

The standard treatment for any type of anthrax is antimicrobial therapy. The dose and duration of an antibiotic or combination of antibiotics will be decided by your doctor based on the severity of your condition. Antitoxin therapies have also been developed in the United States that target the toxin produced by anthrax bacteria. These are particularly helpful in case of inhalation anthrax. Along with medications, you will need to be kept in an intensive care unit for a certain period of time. IV fluids, ventilator support and other medications to help with symptoms are delivered in this duration.

 

Common antibiotics to treat anthrax include ciprofloxacin, doxycycline and levofloxacin. Antitoxins such as raxibacumab and obiltoxaximab can be given if available. 

Prognosis

All forms of anthrax can be cured if the diagnosis is made early and adequate medical treatment is given. Of all types, inhalation anthrax has the worst prognosis if it is not treated immediately. Cutaneous anthrax is the least deadly type. 

Prevention

Anthrax vaccine is available for people who fall in the high-risk category. This vaccine is not for the general public and is only given to individuals between the ages of 18 and 65 who are at risk of contracting anthrax. If you are traveling to an area with a high incidence of anthrax, avoid visiting places with livestock and wild animals and eat well-cooked meat.