Amerithrax (41 page)
At this point investigators still were not totally certain
All of Amerithrax’s letters had contained the same strain of anthrax. It corresponded to the Ames strain in the Northern Arizona University database. NAZU’s was labeled the “reference strain.” It was one of the more virulent strains used in research to “challenge” vaccines and has since been sent to hundreds of research and defense facilities in the United States and Europe for study. They could track the bacteria from its beginning before it was altered into Amer- ithrax anthrax. The Ames strain was originally isolated from a cow in Texas in 1981.
THE
cow chewed gravely under the Texas sun, tossing her head to jerk up clumps of grass. A breeze rustled the yellow pasture and ruffled her short-haired coat. There came the dry rattle of parched grass. She gave a whisk of her brown tail in the stifling heat and swallowed. The life cycle of the anthrax strain that would infest the nation’s mail twenty years in the future had begun.
The cow was grazing in a spore-laden pasture tainted with droppings deposited by sick horses, cows, and goats. Anthrax grew naturally in that earth. Herbivores like this cow acquire it directly from contaminated soil. Under the
Relative temperature, along with varying blood and soil conditions, had determined whether the spores would form or not. Once formed, the durable spores are resistant to tem- perature extremes and dehydration, and are devilishly diffi- cult to obliterate. They can remain dormant, deadly, and capable of growth for twelve years. Outdoors the spores tend to stick to the soil components and do not easily re- aerosolize. Indoor spore accumulations are more airborne.
The cow had ingested anthrax spores in the softened food she was rechewing. The swallowed cud underwent further chemical breakdown in one of the four compartments of her stomach. After water was absorbed, the food entered the “true stomach” where juices further digested the material. From the stomach to the intestine, where digestion and ab- sorption were completed. In an hour, ellipse-shaped spores had begun to germinate. The living anthrax cells absorbed nutriments from their environment.
In the warmth of the cow, the microorganism swirled as chains of two to eight bacilli surrounded by a large capsule that contained polyglutamic acid. An extracellular toxin breached the cow’s germ defenses. The microbes, accumu- lating and bunching, produced edema and hemorrhaging throughout as they made endless copies of themselves. Her bloodstream became a river of poison. Her spleen grew big and black and soon was engulfed by quivering bamboo-like rods and serpentine threads.
The cow grew feverish as the swarming sticks and threads leaked tissue-destroying poison into other organs. She went into shock, twitching and shaking, her nostrils splaying. Circumscribed cutaneous carbuncles appeared throughout her body. In swine similar lesions are found only in the throat. There came a sudden apoplectic attack of sec- ondary shock, an immediate crash. Death occurred a few moments later. In animals, death from anthrax came as sud-
denly as a bolt of lightning. Animals had been known to die standing up.
On his rounds, the rancher found the animal suddenly dead—carcass cold and rigid, legs in the air, and belly dis- tended. Golden-yellow fluid streaked with red oozed from her nostrils—anthrax sputum exudate. Blood from her anus and other orifices was ghastly black. The bacteria of putre- faction from the intestines in the decomposing carcass mul- tiplies without free oxygen. The intestinal bacteria were doing cleanup work, killing off the anthrax bacteria. Tissues from animals dead of anthrax, fresh or putrid or dried or a year old, can only produce anthrax when they contain bacilli or the spores of bacilli.
The real danger lay in the watery blood spilling from the animal, blood now more dangerous than the decaying car- cass. The anthrax bacteria needs its host to die in order that the disease may continue. Spores never form in an animal while it is still alive. They only appear after it has died, and then only when kept very warm. As the tangled blood came into contact with oxygen its microscopic outlines grew dim and faded as the bacteria returned to protective spore form. With the blood, spores drained into the warm ground to take up residence. They would wait patiently to reactivate into ordinary bacilli once more.
Spores are heavy and don’t travel easily by air. And so they waited where they fell until the right conditions for incubation presented themselves. One day the farmer would disturb that patch of stained earth as he plowed a new field. Or a road would be laid, or a flash flood would rush over the spot. Then, the spores would be ingested or breathed or get into a cut to begin their life cycle again—from spore to bacterium to bamboo-like rod and back to tough spore.
A veterinarian arrived on the scene. He knelt and studied the cow. The cow’s sudden death and bloody fluid oozing from every orifice told him he was dealing with splenic fever (anthrax). That infectious, persistent disease was serious business, able to wipe out herds of cattle and sheep, and thankfully rare.
Vets advise that any animals that die of anthrax must be destroyed immediately. If they cannot be burned, they
The rivers and thirsty banks and sloping hills echo to the bleating of flocks and incessant lowing of kine. And now in droves she deals out death, and in the very stalls piles up bodies, rotting with putrid foulness, til men learn to cover them in earth and bury them in pits.
For neither might the hides be used, nor could one cleanse the flesh by water or master it by fire. They could not even sheer the fleeces, eaten up with sores and filth, nor touch the rotted web. Nay, if any man donned his loathsome garb, feverish blisters and foul sweat would run along his fetid limbs, and not long had he to wait ere the accursed fire was feeding on his stricken limbs.
Bacillus anthracis
is one of mankind’s oldest known dis- eases—a daily risk to Bronze Age herdsmen and hunters who were exposed by killing and skinning wild sheep. It had been one of the plagues of medieval days. “Our fields are cursed,” peasants whispered in the green mountains of Auvergne. No flock could venture there without sheep drop- ping until carcasses covered the hillsides like sunflowers. The farmers and horse doctors of Europe had long held strange beliefs of anthrax’s mysterious power.
Wild and domestic hooved, grass-eating animals carry it. Herbivora—cattle, sheep, pigs, horses, antelope, and goats— eat spores with forage as the Texas cow had done. Humans with close contact with infected animals or animal prod- ucts—butchers, tanners, and farmers—become infected through abrasions. Or they might inhale spores from wool and hides or drink contaminated water. In instances of those who consume tainted meat, the bacteria burrows into the digestive tract. (Intestinal anthrax, though, accounts for less than 1 percent of all anthrax cases.)
As the vet studied a culture from the Texas cow under a microscope, he saw the familiar chains of bacilli. They were never found in the blood of healthy animals. His text said:
Bacillus anthracis,
the etiologic agent of anthrax, is a large, gram-positive, nonmotile, spore-forming bacterial rod. The three virulence factors of
B. anthracis
are edema toxin, lethal toxin and a capsular antigen.
However, the polyglutamic acid capsule was lost on an artificial medium like his glass slide. Bacteria isolated from the cow was mailed to Ames, Iowa. Ames lies below Boone and a hundred miles west of Cedar Rapids in the “land where the tall corn grows.” At this time, Iowa farming had suffered a sharp economic downturn and many farms had been lost and lay burning in the sun. The lab where this natural type of anthrax was cultivated, the U.S. Agriculture Department’s National Veterinary Service Lab, was inside a burned-colored, low-slung complex surrounded by equally burned and flat farmland.
The CDC’s lab was at Fort Collins and work on the sam- ple was begun there. In off hours, a researcher at Iowa State University studied drops of the cow’s blackened blood. It was a common virulent strain, but he worked magic with it. Eventually that bacterium would be used in every antibiotic and vaccine study and be the staple of research for years to come.
10
Live spores of attenuate virulence form an effective vaccine for cattle and other animals. A cell-free protective vaccine was shortly produced for use in humans, a sterile filtrate created from a culture of
B. anthracis.
President Eisenhower spoke in Iowa in 1954 to a crowd of twenty-five thousand. Iowa was as central to American politics as it is central in American geography. From the Ames heartland, the bacterium began its travels. In 1981, it was sent to Texas A&M for further study, and from there to the Institute, a key player in the nation’s biowarfare pro- gram. When the sample reached the Institute, it was mistak- enly attributed to the USDA lab in Ames. They just jotted
10
In addition to the 1981 Texas cow strain, only one other Ames isolate was ever reported—from a Texas goat in 1997 and of a type that was not used in the anthrax mailed by Amerithrax.
down the postmark “Ames” and so hereafter it was called the “Ames strain.”
The Ames strain reproduced very rapidly in the right en- vironment and thus was an excellent strain for research. The Institute distributed offspring of the Ames strain of anthrax microbes to as many as twenty labs in the U.S. and abroad. Amerithrax later got his anthrax from one of them. But which one?
The Institute sent a sample of the Ames index strain to the Canadian defense establishment at Suffield (Lab 1), the University of New Mexico (Lab 2), the Battelle Memorial Institute (Lab 3), and, in 1982, the Porton Down Centre for Applied Microbiology and Research in the United Kingdom (Lab 4). Porton Down was the British biological warfare lab and the first to refine the Ames strain.
Porton Down was set in southern England at an old chemical warfare proving ground deep in the Wiltshire countryside. Wiltshire was famous for Stonehenge, an ar- rangement of ancient stone slabs once used as an observa- tory. Porton Down itself was rows of square, flat-topped, three-story concrete buildings. The repellent, forbidding grounds were as empty of life as condemned slums.
Each row was a quarter-mile in length, with two hundred yards separating the rows. The five hundred yards between the slablike buildings and the electrified boundary fence was completely open. There were no trees, bushes, or shrubs, “not even a clump of flowers.” Everything was kept low so no man could hide behind anything. Alsatian man-killers and Doberman pinschers patrolled the fifteen-foot-high outer barbed-wire fence. Electrified, it sloped outward so drasti- cally that the top was four feet out of line with the foot.
In the summer of 1942, Porton Down began testing bio- warfare agents. They proved it was possible to grow anthrax, pack it into a shell, transport it hundreds of miles, and ef- fectively explode it over a precise target area. During World War II, they dropped the West’s first anthrax bomb, a twenty-five-pound prototype, on rugged 550-acre Gruinard Island. The bomb hit amid several dozen tethered sheep at one end of the scenic isle three miles off the northwest coast of Scotland. Most of the sheep perished immediately. The
