The New
York Times
A NATION CHALLENGED: THE DISEASE;
Information
on Anthrax Is Derived From Cases Mostly Outside the U.S.
THIS ARTICLE WAS REPORTED AND
WRITTEN BY GINA KOLATA, WILLIAM J. BROAD AND LAWRENCE K. ALTMAN.
Published: October 12, 2001
Inhalation anthrax, the form of
the disease that killed Robert Stevens, a photography editor in South Florida
is so rare that very few doctors have ever seen it. But anthrax is a common
disease of livestock and other animals in much of the world and the bacterial
spores that produce it are commonplace in the soil of many countries.
In this country, anthrax is rare
even among animals, said Dr. Martin E. Hugh-Jones, an anthrax expert at
Louisiana State University. He said fewer than 100 farm animals contract
the disease in the United States in a typical year.
Cases among people are even rarer,
and the inhalation form is rarer still.
Anthrax is caused by a bacterium,
Bacillus anthracis, and is transmitted by spores that can enter the body
in three ways: it can be inhaled, ingested or can enter the skin through
a scratch or cut.
Worldwide, most people who contract
anthrax get the cutaneous form, in which spores enter the skin, usually
through a cut or a scratch. Most of the time, these cases occur in people
who handle animal hides or wool that contained anthrax spores. In the United
States, 224 human cases of cutaneous anthrax were reported from 1944 to
1994.
In southwest Texas this summer,
a ranch worker became infected after he cut himself skinning a buffalo
that had died of the disease. The man recovered after taking antibiotics.
When anthrax spores infect the
skin, the infection starts out like a small itchy insect bite. The lesion
develops into a pus-filled blister, which crusts into a black scab. Symptoms
include fever, malaise and headache. Untreated, about a quarter of those
affected die because the anthrax bacteria enter the bloodstream, causing
an overwhelming infection and releasing toxins. Treatment with antibiotics
reduces the death rate to about 1 percent.
People who eat undercooked meat
from animals that were infected with anthrax can contract gastrointestinal
anthrax, in which spores germinate into bacteria in the intestines, causing
nausea, vomiting, fever and abdominal pain. Untreated, about 25 to 60 percent
of people with ingestional anthrax die. Worldwide, relatively few anthrax
cases have been gastrointestinal.
Inhalation anthrax, the form that
affected the man who died in Florida, is extremely rare and by far the
most deadly form of the disease. Only 18 cases were reported in the United
States in the 20th century.
How Anthrax Works
Much of what is known about how
the disease progresses was learned from a single outbreak, in the Soviet
Union in 1979, in which 79 people are known to have been infected at once
from an accidental release of anthrax spores being grown in a germ warfare
laboratory on a military base in Sverdlovsk. Sixty-eight of them died and
42 had autopsies.
The disease starts when a person
inhales spores into the lung. Once there, the spores travel to lymph nodes
in the mediastinum, in the middle of the chest, a journey that can take
just a few hours. There, in the lymph nodes, in a process the Sverdlovsk
outbreak shows can take anywhere from days to weeks, the spores in the
lymph nodes turn into anthrax bacteria, which begin producing deadly toxins
that attack body tissues. Because the timing of this germination process
can vary, it is hard to know until about 60 days have passed if a person
who inhales the spores has the disease.
But once the spores germinate,
it does not take long for symptoms to appear, said Dr. Jerome Hazen Smith,
a retired pathologist at the University of Texas Medical Branch at Galveston
who examined autopsy tissues from the Russian anthrax victims. They are
caused by the toxins, which kill cells and cause fluids to accumulate in
tissues.
The first symptoms are nonspecific
-- like fever, cough, headache, vomiting and chills. But within hours to
a few days, the disease enters a second phase. Patients have trouble breathing
because their lungs are compressed by fluid in the mediastinum. They sweat
profusely and go into shock because their blood vessels leak and their
blood pressure drops. About half the patients have blood-filled fluid in
the tissue covering their brains, which compresses the brain, causing coma
and delirium. Once the second phase begins, death can occur within hours.
The disease is so distinctive,
said Dr. David Walker, a pathologist at the University of Texas at Galveston
who helped examine autopsy material from the Russian victims, that a Russian
pathologist, Dr. Faina A. Abromova, recognized immediately what had killed
them. Beneath a victim's skull, she saw a hallmark of inhalation anthrax:
the lining of the brain, filled with blood.
'She said: 'Oh. It's the cardinal's
cap. I remember that from when I was a student. That's anthrax,' '' Dr.
Walker recalled.
Dr. Walker said that, for him,
the blood-filled fluid in the mediastinum, the tissue in the middle of
the chest, was what tipped him off.
Treating Exposed
People
Because there are so few cases
of human anthrax, and because it would be unethical to deliberately expose
people to the bacteria in tests, little is known about treating people
exposed to it. But experiments with animals have provided some clues.
A wide variety of antibiotics,
like penicillin and doxycycline as well as ciprofloxacin and other antibiotics
in its class -- the fluoroquinolones -- can kill anthrax bacteria, but
only if they are given before symptoms appear. By the time a person is
ill, the bacteria have already released large quantities of their deadly
toxins into the body. Experts have recommended treating asymptomatic people
who may have been exposed to anthrax for 60 days.
Ciprofloxacin is the only drug
identified by the Food and Drug Administration as a treatment.
Federal officials say they can
fly supplies of antibiotics and other drugs within 12 hours anywhere in
the county for an outbreak of anthrax or other bioterrorism emergency.
The government has arrangements with drug makers to have fresh supplies
available on an emergency basis.
The government's emergency program
includes the National Pharmaceutical Stockpile, which was mobilized for
the first time in response to the terror attacks on Sept. 11.
The nation's current supply of
anthrax vaccine was licensed in 1970 by the Food and Drug Administration
to prevent the form of anthrax that afflicts the skin. It had proven effective
in clinical trials on factory workers who handled large amounts of goat
hair. In 1985, the Army solicited proposals for pharmaceutical manufacturers
for an improved vaccine. None of the major drug makers bid on the contract.
No war threatened, the disease was rare, and there was little profit in
making vaccines that were not used widely.
This vaccine is now given to military
personnel, but its effectiveness against inhaled anthrax has been questioned.
Its manufacturer, Bioport, of Lansing, Mich., is not now making the vaccine
because its factory does not meet Food and Drug Administration requirements.
Avant Immunotherapeutics, a biotechnology
company in Needham, Mass., announced on Wednesday that it had licensed
some of its vaccine technology to a government contractor that is working
on vaccines against biowarfare agents.
But the company said it could
not comment on what technology was licensed or what pathogens the vaccines
would be directed against. On its Web site, Avant says it has done preclinical
work on a vaccine for anthrax. But the company would not return calls today
seeking comment.
The genome of the anthrax bacterium
is being sequenced at The Institute for Genomic Research, a nonprofit organization
in Rockville, Md. The job should be done in a few months, said Timothy
D. Read, who is in charge of the project there.
Anthrax in History
Anthrax has been known since biblical
times. The fifth plague described in the Book of Genesis as killing the
Egyptians' cattle resembles anthrax and the disease is described in the
early writings of Hindus, Greeks and Romans. An epidemic hit Europe in
the 17th century.
Anthrax bacteria are named for
the Greek word for coal, anthrakis, because they cause coal-black lesions
when they infect the skin. The bacteria's life history -- and the etiology
of the disease they cause -- were discovered in the mid-19th century by
Robert Koch, a German bacteriologist who was a developer of the germ theory
of disease. He was intrigued by the infection, which was occurring among
farm animals in the Wollstein district, where he lived, and set out to
prove that the anthrax bacteria were causing the disease.
Koch discovered that he could
inject mice with anthrax bacteria taken from the spleens of infected animals
and the bacteria would grow in the blood of the mice, giving them anthrax.
But, he asked, could he produce the disease if he used bacteria that had
not been growing in another animal?
So Koch grew anthrax bacteria
in the aqueous humor -- the transparent fluid -- from an ox's eye. That
led him to discover that the bacteria, which are relatively fragile, transform
themselves into tough and resilient spores when they run out of food, or
experience heat or chemical shock. The spores can survive for years in
the soil and it is through spores that the disease is spread.
That is why anthrax does not spread
from person to person -- the bacteria do not produce spores while they
are actively growing in an infected person.
For much of the 20th century,
the world's top militaries investigated anthrax as a weapon, and some even
used it. Germany, for instance, engaged in anthrax warfare in World War
I against Allied horses, which were crucial to the war effort.
In 1998, scientists in Norway
and Britain announced that a lump of sugar from that era contained living
anthrax spores, apparently placed there 80 years earlier by a German spy
intent on disrupting the Allied horse- and reindeer-drawn supply lines
across northern Norway.
Washington first made anthrax
munitions in World War II, fearful that Tokyo and Berlin were making germ
weapons. After the war, the Army built a windowless prototype factory at
Camp Detrick, Md., for making anthrax.
In time, workers there learned
how to increase the potency of anthrax so that a single gallon held up
to eight billion lethal doses -- enough, in theory, to kill everyone on
earth. Two Detrick workers exposed accidentally to the spores died.
During the cold war, Moscow built
a secret anthrax enterprise whose annual production capability of 4,500
metric tons of anthrax dwarfed Washington's one-ton annual effort. The
United States gave up its germ arsenal in 1969. But the Soviet Union, after
signing a global treaty in 1972 that banned biological weapons, worked
even harder to develop them.
Terrorists have tried and failed
to make anthrax weapons. Aum Shinrikyo, a Japanese cult that in 1995 attacked
Tokyo subways with nerve gas, had earlier launched unsuccessful germ attacks
meant to kill millions of people. Its chosen banes included anthrax.
Dr. Richard Spertzel, a former
head of biological inspections in Iraq for the United Nations, said Baghdad
tested crop-dusting gear to spread anthrax before the Persian Gulf war
but had trouble getting it to work.
The hurdles to making anthrax
weapons include getting the right strain of the bacteria. Experts say there
are scores of strains of Bacillus anthracis, only some known to be exceptionally
deadly.
Then a would-be biowarrior would
have to brew swarms of the microbes and then change the growing conditions
so that the fragile rod-shaped bacteria form spores.
Then clumps of spores must be
refined to precise specifications if they are to find their way into the
human lung. Weapons experts say the particles must be one to five microns
wide; 20 of them would line up across the stalk of a human hair.
Dr. Hugh-Jones, the anthrax expert
at Louisiana State University, said terrorists could not simply open a
jar of anthrax spores on a subway or sprinkle some spores around and infect
thousands of people. A person must inhale 8,000 to 10,000 spores to be
infected, Dr. Hugh-Jones said. And, he added, ''getting an efficient aerosol
is a lot of work -- you can't just pump it up in an aerosol can.''
Anthrax spores, Dr. Hugh-Jones
explained, tend to clump together in pieces so big that they would be taken
up by the body's defenses in the bronchi. To make the spores into a deadly
power, ''you've got to have a very, very fine particle size,'' Dr. Hugh-Jones
said. To make that powder, he said, ''you have to use detergents,'' to
break up the clumps. ''It's a professional weapon -- it's not for the amateur,''
he said.
For instance, commercial crop-dusters
usually dispense liquids, and their nozzles produce droplets far too large
for sailing deep into human lungs. A terrorist would have to do major modifications
to adapt the sprayer's nozzles to produce a finer mist of particles.
Nozzle design problems were among
the factors that hurt Iraq's anthrax efforts, Dr. Spertzel said.
Experts say dry anthrax is even
more difficult to make than wet anthrax, but more effective because it
can sail farther on the wind.
Because all anthrax spores are
vulnerable to bright sunlight, they would ideally be dispersed at night,
when the logistics of nighttime aerial strikes can be complex, experts
say. Even then, an attack can fail if the weather is bad or if the spores
are caught up in the rising air currents often produced by the relative
warmth of urban areas.
''People don't understand how
difficult it is to pull off a biological attack,'' said David R. Franz,
a former official in the Army's germ-defense program and now an officer
at the Southern Research Institute, at the University of Alabama.
The Florida Case
Is the Florida case a military-type
anthrax weapon? Scientists familiar with the federal investigation said
no exact match had been made between samples of the Florida bacteria and
other known strains, or subspecies, of anthrax. But they added that preliminary
tests pointed away from its being one of the well-known stains used over
the decades to make anthrax weapons, and away from prevalent strains found
in germ banks, which distribute microbes to hospitals, businesses and universities
for diagnostic purposes as well as research on new medical treatments.
So far, weapons experts say, the
Florida case appears to be crude bioterrorism. Dr. Spertzel, the former
head of biological inspections in Iraq for the United Nations, and William
C. Patrick III, a maker of germ weapons for the United States before President
Richard M. Nixon renounced them in 1969, say the Florida anthrax particles
apparently came in three sizes, which they said would suggest that if a
terrorist planted them he was a beginner.
Very small particles, the experts
hold, would have gone deeply into the first victim's lungs. Larger particles
would have lodged in the second victim's nose. And still larger particles
would have fallen on the keyboard.
''The one thing that's reasonably
certain,'' Dr. Spertzel said, ''is that the Florida case is intentional.'' |