Anthrax by DP Lyle
Anthrax. A strange word. A word that jumps at you. Aggressive. Yet, most people have only recently heard of it and few know exactly what it is. Anthrax has been with us for centuries and today infects 20,000 to 100,000 people throughout the world each year. Not exactly a rare disease. So, what’s all the fuss?
Simple. Anthrax is an infectious disease with a high mortality rate and presents a serious bioterrorism concern.
The disease is caused by a bacterium called Bacillus anthracis (B. anthracis), which is a stubby rod-shaped bacterium that grows in chains. Under a microscope, the bacteria look like a string of purple boxcars or Dominoes placed end to end. B. anthracis is one of the bacterial species that have the ability to form spores, which are basically the bacterial equivalent of eggs. When in a warm, damp environment, such as within the body, they take on their typical rod-shaped bacterial form; when in a dry environment, they become spores. These spores can survive for decades in dry soil and dust. Many infections occur when the microscopic spores invade the body, revert to their bacterial form, and multiply rapidly.
Anthrax is common in herbivoric (plant eating) animals such as sheep, goats, cattle, and horses. The animals become infected as they graze on grasses that harbor the spores and once infected the mortality rate is high. The spores also collect in the animal’s wool or fur. Humans become infected after contact with diseased animals or animal products. Woolsorter’s Disease was common among people who worked with sheep skins, the disease resulting from inhalation of the spores in the wool as they combed and worked it.
Anthrax infections are of three major types:
Cutaneous (Skin) Anthrax occurs when the B. anthracis spores enter the skin through cuts or scrapes or via biting flies. A small red lesion (sore) will appear within a few days, followed by pus formation, ulceration (an eating away of tissues), and finally necrosis (death and blackening of tissues in the area of the lesion). The microbes in the skin may remain localized or may invade the blood stream and cause a severe widespread infection and death. The mortality rate is approximately 15 percent in this form of anthrax.
Gastrointestinal Anthrax is rare and occurs when the victim consumes undercooked meat from an animal with anthrax. Symptoms include fever, nausea, vomiting, abdominal pain and swelling, bloody diarrhea, and death, typically within 24 hours. Mortality rate is over 50 percent.
Inhalation (Pulmonary) Anthrax results from inhaling the spores as in Woolsorter’s Disease and is the most deadly form of the disease. The inhaled spores multiply rapidly in the lungs. Macrophages, which are the immune system’s scavenger cells, consume the bacteria and carry them into the lymph system. The lymph vessels and nodes run throughout the body and are part of the elimination system of our defensive immune network. However, B. anthracis multiplies rapidly when it reaches the lymph nodes of the mediastinum—the central compartment of the chest where the heart lies (the lungs fill the right and left chest compartments). As the bacteria multiply in the mediastinal nodes, the nodes swell, break down, and bleed, causing severe chest pain. Bacterial toxins leak into the blood stream and spread throughout the body, leading to failure of other organs, shock, and death. The disease begins within seven days of exposure. Early symptoms are similar to the flu, which makes diagnosis difficult. During the first two to three days, the victim will develop fever, chills, cough, and shortness of breath. After the organism invades the mediastinal lymph nodes, high fevers, sore throat, severe difficulty breathing, chest pain, shock, and death follow.
Treatment must come early, preferably during the first day after exposure and before symptoms appear. After the disease progresses to the point where the diagnosis is more obvious, antibiotic treatment is poorly effective and the mortality rate soars to nearly 100 percent.
It is important to note that in humans the disease can only be contracted through an animal vector or by inhalation of spore-containing dust or air. It is not contagious from person to person as is the common cold, tuberculosis, or the Ebola virus.
Treatment is with Penicillin plus either Streptomycin or Gentamycin or with Ciprofloxacin (Cipro), though the effectiveness of the latter has not been fully tested. A vaccine exists in limited quantities, but is not publicly available, being reserved for researchers and the military. The vaccine has been the subject of debate since it has been touted as one possible cause of The Gulf War Syndrome (GWS). Proof of this does not exist at present. Since Iraq possessed biological weapons, including anthrax, during the Gulf War, many soldiers were vaccinated against such exposure. The body’s immune response to this vaccine has been blamed for many of the symptoms associated with GWS.
Prevention is simply the avoidance of contact with spores and with infected animals and animal products. Before World War II, Woolsorter’s Disease was all but eliminated in England through the development of methods to decontaminate wool and goat hair.
The current concern regarding Anthrax is its potential as a weapon of bioterrorism. The dissemination of spores via a crop duster or sprayer or by low altitude release from a plane could result in wide spread infection. The placement of a canister of spores in a ventilation system could spread them throughout a building.
But, as with any highly infectious and dangerous biologic material, handling anthrax is difficult. There is considerable risk that the potential terrorist could do himself in long before disseminating the infection or at least at the same time. Biomedical researchers, who work with anthrax, invariably wear Haz-Mat (hazardous materials) suits just as they would if handling Ebola or any other aggressive infectious agent. Also, anthrax spores are not easy to come by. Obtaining, storing, transporting, and disseminating the spores is difficult at best and danger would dog each step.
A potential terrorist would have to obtain the bacteria from a lab or a diseased animal or extract the spores from contaminated soil. A sterile and airtight lab would then be needed as a place to cultivate the bacteria in large quantities. Once sufficient amount of the bacteria was grown, it would need to be dried so that the bacteria would sporolate (form spores). The spores would then be packed into canisters or compressed into pellets and stored in an airtight container.
The “farmer” would have to wear a Haz-Mat suit at all times and would need a decontamination system for this suit each and every time he entered and exited his “lab.” Strict sterile technique would be required in each and every step of the process. Since this would require specialized equipment, a controlled environment, and a working knowledge in handling biohazardous materials, it is unlikely this could be accomplished in your garage or basement.
After manufacture of the spores, the transportation to the planned exposure site and the loading of the chosen dissemination device would also require strict sterile handling. A difficult and treacherous task.
However, if the terrorists were successful, a major catastrophe could result. In such wide spread contamination, the public health services would be quickly over-run. Most doctors and other healthcare professionals know little about anthrax. We learned about it from medical textbooks and few of us have ever seen a case in our practices. And since the early symptoms are identical to a routine cold, viral infection, or flu, the diagnosis is rarely considered. An old medical adage is that “common things occur commonly,” so anthrax doesn’t jump to the top of the list possible diagnoses in someone with fever and fatigue. The first few cases would likely be misdiagnosed, so that by the time the true nature of the illnesses were discovered not only would the initial victims be beyond help, the number of infected persons could be huge. Besides, with an incubation period of up to seven days, the exposure could be widespread before the first case appeared.
The vaccine is in very limited supply and an epidemic would likely overload the hospitals and healthcare personnel in short order. Still, the fact that it has no person-to-person transmission is in our favor. Let’s hope we never have to face this situation.
DP Lyle, MD