Anthrax as a weapon of terror may have roots reaching back to two plagues that visited Biblical Egypt.
Anthrax: A threat nearly as old as mankind
By Sallie Baliunas, Ph.D. (December 1, 2001)

[OBJECTIVE SCIENCE.COM] On June 8, 2001, President George W. Bush called for remediation of the threat of biological warfare because it is one of the "true threats of the 21st century." His words proved prescient, as by September this nation suffered the world's first bioattack of the 21st century with anthrax.

As investigators scratch for leads as to the source of strains of anthrax and the perpetrators of bioassaults taking the lives of people as divergent as a Florida reporter, Washington postal workers and a grandmother in Connecticut, they are dealing with a threat nearly as old as mankind.

Anthrax as a weapon of terror may have roots reaching back to two plagues that visited Biblical Egypt. In Exodus Chapter 9, one of those plagues was described as a "very rare pestilence" on sheep, cattle, camels and oxen. For the next plague, Moses was directed to toss ashes on the wind, which "will become fine dust" that attacks both "man and beast" with boils and pustules. The stated rarity, association with grazing animals, dissemination by motes of dust or ashes and appearance of boils suggest anthrax, a bacterial disease.

The symptom of skin lesions described in Exodus may have been the less deadly cutaneous form of anthrax. It infects the body through the skin, one of three forms since identified by science for anthrax disease. Inhalation, or pulmonary, anthrax that enters through the lungs, is the cause of the six deaths in this country since Sept. 11. Its lethality and difficulty to cure make it a potent bioweapon.


Anthrax: Bacteria and Pathogen

The source for all anthrax infections is a common bacterium, Bacillus anthracis. Bacteria fall generally among one of three classes by shape: sphere (coccus), spiral (spirillum) and rod (bacillus). So, anthrax is rod shaped. It is relatively large as bacterial sizes go – as big as 2 by 10 microns, or roughly one by five ten-thousandths of an inch.

Not all bacteria are deadly. They often survive by living off host organisms, even benefiting their hosts. Of the rod-shaped species, many are harmless; in contrast, anthracis is lethal, especially when inhaled. And because it causes disease, that makes anthracis a pathogen.

Pathogens that kill their host often survive because they can move to other hosts as they come in contact with them. Spores need to invade directly each victim. Anthrax bacilli normally attack herbivores such as sheep, horses, goats and cattle, and when an infected animal dies, the bacilli escape the carcass to form spores that guard their genetic code or DNA with an exceptionally durable capsule. Effectively protected against deterioration in the environment, the spores of anthrax bacilli can persist decades. They can contaminate soil and infect new hosts, primarily the herbivores. Insects that feed on live infected animals or vultures that consume carcasses also can spread the spores.

But while anthrax is not contagious from person to person, its pulmonary form is particularly virulent. Once inhaled, spores move fast from the lungs to the lymph nodes near the heart and major blood vessels. The entering spores, viewed by the host as an invasion by a foreign body, trigger a counterattack by one of the human body's remarkable defense systems, the white blood cells. They ingest and attempt to digest the spores to destroy them. But encased in their protective coats, the tough spores may survive, and then scavenge metabolic material from the white blood cells in order to reproduce. Within a day or days, newly made anthrax bacilli burst from the white blood cells, hungering for more host cells and discharging toxins. Those toxins are extremely potent, destroying surrounding body tissue and rapidly overwhelming the host with blood poisoning, organ failure and death.


Getting It Under Control

Ironically, for all the devastation anthrax can sow, the study of anthrax itself led to a tremendous advance in conquering many horrific infectious diseases.

The great chemist Louis Pasteur in the mid-19th century founded the theory that microorganisms, or "germs" were microscopic agents of infectious disease. Other of Pasteur's great accomplishments include the development of the pasteurization process to keep milk supplies safe, discovery of the agent of silk worm disease, and creation of a vaccine successful in preventing hydrophobia, or rabies.

With germ theory gaining consideration as a cause of infectious disease, Robert Koch in 1876 proved that bacillus anthracis is the bacterium that produces anthrax. Pasteur then not only confirmed the bacillus as the germ responsible for anthrax, but also worked to reduce the bacteria to a less potent state. The weakened, or "attenuated" form of the bacillus was employed as a vaccine that, when injected into potential animal hosts, tries to stimulate the body's immune system to recognize and defend against a future invasion by the bacillus. The early anthrax vaccinations were of limited success, in part because of anthrax's virulence. Yet, astonishing success against other diseases derived from Pasteur's study of the technique of vaccination and germ theory.

Vaccination has vanquished many infectious diseases and so lengthened the human life span. But even as the anthrax vaccine to prevent infection has improved, it is not yet ready for widespread inoculation of the population. That leaves treatment after exposure, when antibiotics are given to attack the bacilli created in the host. Because the bacilli reproduce rapidly, antibiotic therapy must ideally begin just after exposure – often a fact difficult to assess. The race to kill the bacilli before they massively reproduce is crucial in surviving anthrax because of the toxin's lethality.


The Allure of Bioterror

The lethality -- coupled with the hardiness and persistence -- of bioterror agents such as anthrax that has prompted governments to fear for civilian safety and establish something of a breakwater against their widespread use.

President Lincoln, during the Civil War, was among the first leaders to direct troops to spare or protect civilians and civilian institutions when possible. His "General Orders 100" for Federal Troops became a building block for codes of conduct developed at international conferences at The Hague in the Netherlands in 1899 and 1907. Among atrocities prohibited by codes written there were the use of poison gas or other poison during warfare.

Yet, just as General William Tecumseh Sherman destroyed civilian property in his race to the sea during the Civil War, combatants in World War I, including the United States, used murderous chemical agents like chlorine, mustard gas or phosgene despite international pressure.

And subsequent agreements, such as the 1975 Biological and Toxin Weapons Convention, signed by almost every nation and forbidding developing or stockpiling biological agents for other than peaceful purposes, have not eliminated bio or chemical weapons as a threat.

The Soviet Union, despite signing the 1975 convention, appears to have disobeyed it with tragic consequences for their own people. Tantalized by its potential to provide a strategic advantage, the Soviets escalated bio-weapon development, leading in 1979 to the accidental release of anthrax from a lab in Yekaterinburg at Sverdlovsk. The plume of vapor released in that accident killed at least 66 people.

It was from that event that the incubation period for the disease was estimated to be as long as 43 days after exposure, leading to current prophylactic treatment by antibiotics for 60 days.


Technological Help

As America has learned, though, the anthrax threat must be fought at many levels. One way is to try to prevent terrorists from getting the spores. Equally important is to enhance protection and survival should anthracis's deadly spores be criminally dispersed. That includes techniques to sterilize, e.g., by irradiation, contaminated environments. As biology enters the post-genome era, hope brims from scientists' drawing boards sketched with ideas of futuristic vaccines and antibiotics to diminish anthrax's lethality.

But because it is the toxin that causes death, technological efforts to weaken the toxin would improve chances for survival as antibiotics work to eradicate the invading bacillus from the host. Researchers at Harvard, for example, are developing a synthetic chemical that may decrease the virulence of the toxin. Other researchers are studying the toxin through genetic modification.

The struggle with biological agents is nearly as old as civilization itself. And in the hands of terrorists or rogue states, as President Bush noted, bioweapons pose a threat to civilization.

 
-- Dr. Sallie Baliunas is a co-host for http://www.techcentralstation.com/
Sallie Baliunas, Ph.D. is an Astrophysicist at the Harvard-Smithsonian Center for Astrophysics and Deputy Director of Mount Wilson Observatory. Dr. Baliunas serves as Senior Scientist at the George C. Marshall Institute in Washington, DC, and chairs the Institute's Science Advisory Board. She has written over 200 scientific research articles. In 1991 Discover magazine profiled her as one of America's outstanding women scientists. She received her M.A. (1975) and Ph.D. (1980) degrees in Astrophysics from Harvard University.
 

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