All About Anthrax

WHAT IS ANTHRAX?

Bacillus anthracis is a rod-shaped bacterium that typically appears--when outside a living host--in a dormant state, protected by a hard-shelled spore. Provided it is lodged in rich soil subject to dramatic changes in climate, the organism can and does persist in this form for many decades. As a general matter, anthrax spores germinate to produce multiplying vegetative forms only after infecting a living host. That host is most commonly a herbivore which, grazing in an anthrax-contaminated field, ingests the bacillus along with its feed and is then infected through some preexisting gastrointestinal lesion.

Once inside the body of a cow, for example, anthrax spores are carried to its lymphatics, where they begin to germinate. The first vegetative bacilli entering the cow's blood stream are effectively filtered by the animal's reticuloendothelial system. But even then the bacilli are releasing toxins, which soon overwhelm the poor beast. As the disease approaches its end stage, the number of anthrax bacteria in a host can double in less than two hours, and this chaotic growth eventually produces massive toxemia that destroys the endothelial cell lining of blood vessels. Death comes with what World Health Organization guidelines rather daintily describe as a "characteristic terminal hemorrhage to the exterior."

Recent newspaper coverage has proved similarly squeamish about the grisly reality of a lethal anthrax case, for the same is true in human patients: Uninterrupted by medicine, the disease causes the vascular system to explode, releasing a horrifying quantity of blood through the victim's mouth, nose, and other orifices. From an animal corpse lying in a field, this infected blood then soaks into the soil, where bacillus anthracis returns to a sporulated, dormant state--awaiting the next unfortunate herbivore.

IS ANTHRAX AS RARE AS THEY SAY?

Not in animals it isn't. Cases of livestock anthrax are reported almost every year throughout the world. Spain, Albania, Italy, and Romania suffer significant outbreaks on a regular basis. Turkey, Greece, and Russia are subject to widespread infections. The Middle East and Central Asia comprise an "anthrax belt" in which severe epidemics are commonplace. Chinese livestock are riddled with anthrax in most sections of the country. Australia experienced a major epidemic in early 1997. The disease is endemic in Mexico, Honduras, Nicaragua, and Costa Rica, and hyperendemic in El Salvador, Guatemala, and Peru.

Here in the United States, livestock vaccination and antibiotic prophylaxis have become almost routine during the past few decades, and anthrax outbreaks are recorded at nowhere near the levels they were before World War II. But they are not unheard of; Texas has a particular problem, with 56 separate confirmed incidents between 1979 and 1997. And there and elsewhere, ironically, American veterinary medicine's increasing inexperience with the disease may well mean that many outbreaks go undiagnosed--and last long enough to threaten surrounding human populations.

In its September 15, 2000, Morbidity and Mortality Weekly Report, for example, the Centers for Disease Control described how, two months before, a farmer in Roseau County, Minnesota, had killed, gutted, and skinned a cow that was "unable to rise." A local vet approved the farmer's plan to slaughter the cow for consumption, and the carcass was taken to a custom meat-processing plant. Two weeks later, members of the farmer's family began eating hamburgers and steaks cut from this carcass, and two of them promptly experienced severe gastrointestinal symptoms and/or high fever. Laboratory tests confirmed the presence of anthrax bacilli in the processed meat. The affected family was prescribed heavy doses of precautionary antibiotics and both patients fully recovered.

HAS NATURALLY OCCURRING ANTHRAX EVER BEEN A SIGNIFICANT HUMAN HEALTH PROBLEM?

Yes.

Throughout much of recorded history, anthrax has periodically devastated both rural and urban populations. For instance: The mystery has never been solved definitively, but more than a few medical historians have long believed that the 430-427 b.c. "plague of Athens," a famously gruesome, eyewitness account of which appears in Thucydides' "History of the Peloponnesian War," was a bacillus anthracis pandemic. Certain symptoms Thucydides described--fever, bleeding, and "small pustules and ulcers"--are strikingly consistent with a severe form of cutaneous anthrax infection, in which the bacteria enter the body through abrasions on the skin, which then breaks out into ulcerating lesions and large, scabby "eschars." It is from the color and discomfort of these characteristic eschars, incidentally, that the anthrax bacillus derives its scientific name, after the Greek word (anthrakis) for "burning coal."