Our Small World

What's the Bio in Bioterrorism?

One of humankind’s worst ideas has also been one of its most persistent: the notion of deliberately using germs as weapons. Today, experts worry that terrorists may adopt this grim tactic, so they work to protect the public.

Humans have two principal types of immunity— innate and acquired. Immunity is your body’s ability to fight disease.

Innate immunity (or natural immunity) is your body’s first line of defense against infection. It includes anatomical features—skin, mucus, and nose hair—that act as physical barriers keeping germs or microbes from getting in. There’s more. It also includes the body’s ability to fight any invaders that find their way inside. The innate immune system attacks microbes, but has no memory of prior attacks by the same microbe.

All plants and animals have some form of innate defensive system. All mammals and an unknown number of other vertebrates have an acquired (adaptive) immunity. It makes antibodies that are designed to fight specific germs. If those germs reappear, moreover, your body remembers them and is ready to fight them again. This added immunity can last for a limited time—or for a lifetime. Dengue fever is one notable exception. For reasons that are not well understood, Dengue can be far more serious the second time around.

Acquired immunity results from exposure to a microbe or is induced through vaccination. Thus, vaccines work by triggering your acquired immunity. Explore more in Science & You, below.
An antique image shows the bodies of plague victims piling up outside a European city.
Source: National Institutes of Health

No one knows who were the first bioterrorists. That dubious honor may belong to Assyrian warriors in the sixth century B.C. They used a deadly fungus to poison the wells of their enemies. Germ warfare remained alive and well in the year 1346, when the Tatars attacked the Crimean city of Caffa on the Black Sea. They had suffered an outbreak of plague and decided to share it with their foes. To do so, they hurled the infected bodies of the dead over the city walls. Fleeing residents carried the disease to Italy, sparking Europe’s second major epidemic of the Black Death.

Beginning in 1492, the Europeans who came to America unknowingly brought with them diseases that wiped out huge numbers of natives. A few documented instances of purposeful bioterrorism occurred during the French and Indian War (1754-1767), when Britain and France vied for control of North America. British forces distributed smallpox-infested blankets to Native Americans who had sided with the French.


In a December 4, 1775, letter to the Continental Congress, Gen. George Washington reported hearing a rumor that the British were trying to spread smallpox near Boston. He called smallpox his "most dangerous enemy."
Source: National Archives

Interest inbioweapons intensified in modern times. Japan used them in China during World War II, and the Soviet Union developed an ambitious bioweapons program. Its dark achievements included creating an airborne form of the smallpox virus. The disease could then be loaded into bombs and missiles. The United States launched its own bioweapons effort, reportedly testing delivery devices (armed with harmless germs) in American cities.

More recently, countries around the world have thought long and hard about bioweapons. During the 1970s, a group of nations, led by the U.S., negotiated and signed an agreement known as the Biological Weapons Convention (BWC). It went into effect on March 26, 1975. The BWC bans the development, production, and stockpiling of almost all bioweapons. (There were some exceptions for self-defense.) So far, more than 170 countries have signed the agreement.


Happy ending, right? Not exactly. The BWC does not contain any real way to make sure that countries actually obey its restrictions. In the late 1980s, top Soviet scientists defected to the U.S. and revealed that their country had continued to develop bioweapons long after signing the BWC. In fact, 32,000 scientists and staff had comprised Biopreparat, the largest and most comprehensive covert biological weapons program in world history. Anthrax was among their specialties. Another signatory, Iraq, also created bioweapons during the 1980s. Even worse, it admitted it was actually ready to use them as a weapon in 1991.

That same year brought another bioweapons milestone: the collapse of the Soviet Union. It splintered into 15 different countries, the largest of which is Russia. Officials in those countries have reported that the Soviet bioweapons program is dead. They also claimed to have destroyed stockpiles of the smallpox virus. Not everyone is sure whether to believe them, though.

That raises the possibility that stashes of bioweapons may lurk in Earth’s shadier corners. That, in turn, sparks a disquieting question: What would happen if terrorists got their hands on such nasty stuff? To explore that hot topic, let’s look at three diseases with bioweapon potential: anthrax, Ebola fever, and smallpox.


Anthrax is largely an animal disease. It exists among cows and other creatures that live in herds. It is caused by bacteria known as Bacillus anthracis. Now and then, the disease makes the leap from animals to humans. This can happen when people come in contact with infected animals or products made from them.

In humans, anthrax can afflict the skin, the lungs, or the digestive system. Skin cases are unpleasant, but usually not too dangerous. Inside the body, though, the disease can be deadly.

Americans saw the lethal power of anthrax in September 2001. Bioterrorists took anthrax endospores, or cells, and ground them into a fine powder. They stuffed the powder into envelopes, which they mailed to prominent Americans. Along the way, the disease infected 22 people, particularly postal workers, from Connecticut to Florida. Five died. The senders of these bioweapons have yet to be caught.


An anti-bioterrorism squad in Washington, D.C., demonstrates techniques for cleaning up after the 2001 anthrax attacks.
Source: Stanford University


Federal and state officials have developed plans for combating similar attacks. Their strategies include training emergency response teams and developing a national database to track cases. They also maintain supplies of vaccines and antibiotics to use in the case of an outbreak.


This poster tells people in the African city of Kikwit how to avoid catching Ebola fever.
Source: Centers for Disease Control and Prevention

Ebola is a disease caused by a virus. It gets its name from the Ebola River in the Democratic Republic of the Congo, and it exists primarily in Africa. The disease causes bleeding throughout the body, killing a large percentage of those who develop symptoms.

Researchers believe that humans catch Ebola from coming into contact with an infected animal. Although the virus is hard to spread, Ebola can be transmitted from person to person, via direct contact with the blood or secretions of someone who is infected. This usually occurs when a family member or healthcare provider cares for a person with Ebola. They can also be exposed to the virus via an object used by a patient.

Visit the CDC to learn about all documented outbreaks since 1976.

As far as we know, Ebola has never been used as a bioweapon. Experts fear, however, that bioterrorists could modify the virus, giving it the ability to spread more easily. That’s a scary prospect, because diseases like Ebola are so effective at killing people. The National Institutes of Health has created a vaccine for prevention of Ebola in monkeys that is now being tested for its effectiveness on humans.


click to enlarge image
Pocks, or sores, mark the faces and limbs of small-pox patients. These sores give the disease its name.
Source: University of Alabama at Birmingham

Smallpox is one of the most dreaded diseases in human history. Caused by the variola virus, it spreads quickly from person to person. It causes pocks, or sores, to break out all over the infected person’s body. If the patient survives, the pocks will leave lifelong scars.

On a brighter note, smallpox is the one disease that humans seem to have wiped from the globe. Between 1967 and 1977, a World Health Organization (WHO) campaign eradicated naturally occurring smallpox. The last known case in the U.S. occurred in 1949, and the last known case in the world occurred in Somalia in 1977. Yet samples of the variola virus exist in two WHO labs, one in Atlanta, Georgia and one in Russia. Scientists continue to debate whether to destroy these last

United Nations patches celebrate the wiping out of smallpox.
Source: U.S. Department of Health and Human Services

smallpox viruses or to keep them in case the need arises for further research. One fear is that the virus may be held secretly in other places as well.

Experts believe the likelihood of using smallpox as a bioweapon is fairly small. Still, officials want to be prepared. After the terrorist attacks of September 11, 2001, the U.S. government asked pharmaceutical companies to produce batches of the smallpox vaccine. These are kept on hand to be used in the event of a bioterrorism strike or other outbreak.



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