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History of Biological Weapons

Humans have a long history of trying to poison or infect others, particularly in warfare—and long before scientists discovered germ theory. In the ancient world at least three types of actions were commonly used: poisoned arrows or garments, infecting/poisoning a food or water supply (especially with corpses and dead animals), and use of venomous/toxic animals against enemies (snakes, bees, scorpions, etc.)(10).

During the 14th-15th centuries biological agents were used to end sieges during medieval wars (11). In what is now northern France at Thun L’Eveque, 1340 AD, dead animals were launched into the castle. The castle defenders reported, “the stink and air was so abominable, that they considered how that finally they could not long endure.” A short while after the biological attack the defenders of the castle negotiated a truce and later abandoned the castle.

In 1346 at Kaffa now present day Feodosia, Ukraine, humans in the attacking Tartar army who had died of plague were launched into the castle. An outbreak of plague in the castle ended the siege. While fleeing Kaffa, some believe that, these infected refugees may have carried the disease to Italy, contributing to the second major epidemic of "Black Death" in Europe during the 1300’s (12).

The launching of dead soldiers into the castle may, however, be an overly simplistic view of the cause of the plague outbreak in the castle at Kaffa. In fact some believe it might not even be an example of biological warfare but rather an example of a natural plague outbreak relatively common in that day. Fleas are the principle vectors in transmitting the disease from infected rats to humans. Rat to human transmission via fleabites is the most common means by which plague epidemics begin. Fleas usually abandon dead bodies so it is unlikely that launching a few dead bodies into the castle would have caused an outbreak of this disease. Plague outbreaks were not uncommon at this time. In fact, the Tartar army outside the castle reported that their comrades died of this particular disease. Others believe that the plague may have been brought to Kaffa by a naturally occurring cycle in which plague infected rats from the wild intermingled with urban rats in Kaffa causing large numbers of the urban rats to die. This left the fleas who spread the disease no place to get a blood meal but from humans, thus starting the plague in the city (13). Regardless of how the plague started in Kaffa the biological agent, Yersinia pestis, helped the Tartar’s take their objective.

In 1763 during the French and Indian War, British Gen. Jeffery Amherst the commander at Fort Pitt, Pennsylvania ordered blankets and handkerchiefs from smallpox victims be given to the Delaware Indians at a peace-making parlay (14). Historical records indicate that Amherst clearly wanted to, “Extirpate this execrable Race” (15, 16). However, there is no definitive evidence that his “gift” of smallpox-contaminated blankets actually caused the smallpox epidemic that occurred in the Delaware Indians the following spring. Amherst clearly intended on giving the Indians smallpox however, other outbreaks of smallpox were occurring at the same time decreasing the certainty that these contaminated blankets caused the smallpox outbreak. In any case the Delaware Indians defending Fort Carillon sustained epidemic casualties, which contributed to the loss of the fort to the English (14, 16).

Smallpox contaminated blankets were also believed to be used to spread disease to others throughout the colonies even through the Civil War. However, there is little data to show how effective these BW attacks were.

During the Revolutionary War it is reported that the British tried to transmit smallpox to the Continental Army. In WWI from 1915-1918 the Germans used biological agents to attempt to cause severe disease (glanders and anthrax) in the horses and mules used by the Allies (17). However, no one knows for sure if the animals that did die during the voyage across the Atlantic were due to glanders, anthrax or whether their deaths were due to some other factor. Once again most reports indicate that these attacks were not very effective (8).

The Japanese developed biological weapons under the command of General Shiro Ishii (1932-1945) and Kitano Misaji (1942-1945) (13, 17, 18, 19, 20) during the Sino-Japanese war (1937-1945) and World War II. The Japanese program built several facilities in cities all over China. The most commonly sited program began in 1937, located 40 miles south of Harbin, Manchuria, in a laboratory complex code named "Unit 731". Ishii became convinced of the potential of biological weapons in the 1920’s and he lobbied his superiors persistently until he was assigned to develop a BW program in their fight against the Chinese. Unit 731 eventually contained 150 buildings, 5 satellite camps, and a staff of more than 3,000 scientists and technicians. In 1939 Ishii began field tests using the BW they had developed using prisoners, indigent Chinese and prisoners of war. A post WWII investigation revealed that the Japanese had examined many organisms for their use as BW.

Over the next three years the infamous Japanese Army Units 731 and 100 carried out biological attacks on military and civilian targets. They used saboteurs to contaminate water wells with bacteria that caused intestinal diseases, distributed food laced with disease-causing microorganisms, and air-dropped fleas infected with the plague bacterium. In 1940, a plague epidemic in China and Manchuria followed reported sightings of Japanese planes flying over the area. Many believe they dropped plague-infected fleas on the areas. By 1945, the Japanese program had stockpiled 400 kilograms of anthrax to be used in a fragmentation bomb. The Japanese BW program (1932-1945) killed between 5,000 and 10,000 prisoners as a result of experimental infections or execution following experimentation. Some believe that several hundred thousand Chinese casualties were the result of Japan’s BW attacks. However, this is disputed and estimates of casualties vary widely from 1,000 to over 222,000 (8). Studies continued at Unit 731 until 1945, when the complex was destroyed after the war.

Even though Unit 731 was destroyed the U.S. and several other nations prevented the scientists in this unit from being prosecuted for war crimes but rather took them from Japan to their countries to help with their own fledgling BW programs. At that time the BW program in the U.S. had a built at least 4 different BW facilities (13).

Many different countries began biological weapons programs in the 1920s, 1930s, or 1940s (Table 1; 8, 16, 20). The BW program was terminated in France, following its occupation in 1940. The defeat of Germany and Japan in 1945 ended their BW programs. The British and Canadian BW programs ended soon after World War II (8, 13, 20). 

Table 1: Year(s) Various Countries Began Their Biological Warfare Program (7, 8, 20)














1922-1928 and 1934-1940

North Korea




South Africa




United Kingdom




Union of Soviet Socialist Republics




United States of America





 However, the cold war following WWII between the United States and the Union of Soviet Socialist Republics (USSR) kept their biological weapons programs going full steam ahead. Both nations invested large amounts of time and money to develop substantial stockpiles of biological agents and the means to send those agents behind enemy lines. Both countries examined the potential military use of many different bacteria, viruses, and biological toxins. Methods to deliver the BW as a fine-mist aerosol, to package them in bombs, and to launch them in missiles were developed and tested. Methods to assassinate individuals with BW were also developed.

The U.S. offensive BW program began in 1942 or 1943 (there is some disagreement among sources concerning the time the program began; 8, 13, 20) under the War Reserve Service, a civilian agency. The program began with a research and development facility in Fort Detrick, Maryland, testing sites in Mississippi and Utah, and a production facility in Terre Haute, Indiana (13). Unfortunately, adequate safety measures were not built into the production facility and testing revealed BW contamination of the plant and its environs. These findings slowed further development of large-scale production during WWII. However, they did produce 5000 bombs containing anthrax.

After WWII Japanese scientists were brought to the U.S. from Unit 731. They were granted immunity from war crimes prosecution if they would disclose information concerning their BW program. Some indicate that these Japanese scientists did little to help the expanding U.S. BW program (8). The BW program expanded during the Korean War (1950-1953). A new production facility was built with adequate safety measures in Pine Bluff, Arkansas. Large-scale production of BW was conducted in this plant starting in 1954. The U.S. also started a countermeasures program, which included vaccine, antisera, and antibiotic production and stockpiling. This program was designed primarily to protect military personnel (13).

Military and civilian volunteers were used in experiments started in 1955. Biological munitions were detonated in a 1-million liter, hollow, metallic, spherical chamber at Fort Detrick. This sphere called, the “eight ball” was used to expose human volunteers to Francisella tularensis (tularemia) and Coxiella burnetii (Q fever). They conducted these studies to test how vulnerable humans were to aerosolized pathogens and to determine the efficacy of various therapeutics (13).

Other supposedly nonpathogenic organisms (simulants) were used to test the ability of BW to spread once released into the air. New York City and San Francisco were surreptitiously used to see which means of aerosolizing BW worked best, to study the effects of sunlight on the viability of the aerosols, to determine how wind and weather affected the aerosols and to characterize the behavior of aerosols over large geographic areas. Some believe a Serratia marcescens simulant release in 1951 may have caused an outbreak of urinary tract infections at Stanford.  Several other outbreaks of disease due to these bacteria were also thought to be due to the release of a simulant. However, the bacteria from patients supposedly infected by the simulant were antigenically different than the bacteria used by the military in their simulant release experiments. Regardless of whether these simulants actually caused these outbreaks simulant releases ended by 1968 (13)

It was not until 1976 that the general public was made aware of the simulant release experiments. Public outcry resulted in several unsubstantiated claims of disease outbreaks following simulant releases. Senate hearings were conducted in 1977 and the army was severely criticized for its continued use of simulants following the Stanford outbreak (13)

Animal studies were also performed at Fort Detrick and open-air studies were conducted at remote desert sites and in the south Pacific. One of the last of these open-air tests was conducted in 1969 upwind of a small atoll in the south Pacific. They used a jet, caged Rhesus monkeys on barges, and an unknown BW to test the effectiveness of this method of warfare. Barges containing caged Rhesus monkeys were positioned up to 50 miles downwind of the Atoll. A jet flew in past the upwind side of the Atoll and released the BW into the air. The wind carried the powder now a long thin cloud past each barge. Over the next few days half of the monkeys died. Some of the monkeys in the barge fifty miles away from the BW release also died (13, 16, 21, 22).

Later that same year, on November 25th, President Nixon issued an executive order that unilaterally and unconditionally renounced all methods of biological warfare. This order ended the U.S. offensive BW program and resulted in the destruction of the nation’s BW program and BW stockpiles. Henceforth the U.S. BW program would be confined to research on strictly defined measures of defense, such as development of diagnostic tests, vaccines and treatments for BW.  The following year on February 14th President Nixon ordered the destruction of all toxin weapons. However, the Central Intelligence Agency did not comply and illegally retained samples of the biological toxin ricin. In 1975 a congressional hearing admonished the CIA for its noncompliance (13).

Many felt the U.S. terminated their BW program because of concerns that military personnel were not prepared to handle BW and that BW were untried, unpredictable and potentially hazardous to the users as well as those under attack (13). However, others argue that BW were adequately tested and proven to be quite predictable. Similar measures used to protect troops during chemical weapons attacks during WWI would also protect troops in the field during a BW attack. They state that the U.S. government was more concerned with a continuing proliferation of BW programs in other countries. Many at that time believed other countries would feel compelled to start their own BW programs making the world even less stable. Several countries wanted to start WMD programs to tip the balance of power in their favor. Many analysts also knew that production of BW would be a less detectable WMD to develop than a nuclear WMD program. Therefore, some conclude that the U.S. ended their BW to slow the proliferation of BW as a WMD (8, 20, 23).

Meanwhile the USSR began in 1926 what eventually became the largest, most ambitious, and most advanced covert BW program on earth. A new BW facility was built in Sverdlovsk in 1946 and another was built in 1953 in Kirov. In time four different BW institutes were created under the Ministry of Defense. Several other government ministries also conducted BW research and development programs: Ministry of Agriculture, Ministry of Health, and the Academy of Sciences (8, 20).

In 1973, the USSR began a major expansion of their BW programs and created the Biopreparat or “The System”. They built around 8 production facilities and several standby BW production factories of enormous capacity that they could use if directed to during war. Stockpiles of tens of tons of three anti-human biological agents were allegedly maintained. Not only did they work with existing strains of BW they also genetically modified certain bacterial BW agents making them resistant to many of the antibiotics used in treating people exposed to these agents. Fortunately, no stockpiles of the genetically modified agents were produced. In time there may have been as many at 40 to 50 different institutions in the USSR working on BW. They employed a total staff of about 60,000 (support staff, technicians, and scientists). They also did some open-air testing of their BW on an island on the Aral Sea. Meanwhile, most of the world was oblivious to this enormous BW program (8, 13, 20, 24).

In 1979, an outbreak of anthrax in the city of Sverdlovsk killed nearly 70 people. The Soviet government publicly blamed contaminated meat, but U.S. and U.K. intelligence sources suspected the outbreak was linked to secret BW work at a nearby lab. During the 1980s various intelligence agencies became more and more convinced that the Soviets had developed a large BW program. However, it was not until between late 1989 and 1992 that the British and American governments were able to confirm their suspicions. Defectors in senior management positions from the USSR’s BW program provided information to the U.S. and U.K. that led to concerted efforts by the U.S./U.K. to get the Soviet program closed down. This information was not given to the public until several years later (8, 13, 20).

In 1992, President Yeltsin admitted that the outbreak of anthrax in Sverdlovsk was due to an accidental release from a Soviet Ministry of Defense research and development facility. The dissolution of the USSR by the Supreme Soviet in 1991 and President Yeltsin’s Decree in 1992 to stop BW production many believe spelled the end of their BW program. After the dissolution of the Soviet Union, Russia allowed inspectors to talk with people in and around Sverdlovsk. They were able to confirm that an accidental release of anthrax from the BW plant killed the Sverdlovsk citizens. However, it is still uncertain whether the entire BW program was destroyed (8, 20). 

Iraq began its a BW program in 1974. By January 1991 Iraq had produced large quantities of anthrax, botulinum toxin, Clostridium perfringens, aflatoxin, and small quantities of ricin, and had more than 180 biological weapons deployed to five hide sites. After Desert Storm ended, UN inspectors determined that Iraq had bombs, Scud missiles, 122-mm rockets, and artillery shells armed with botulinum toxin, anthrax, and aflatoxin. They also had adapted spray tanks fitted to aircraft that could distribute BW. Fortunately, the opening Desert Storm bombardment of January 17, 1991 destroyed the only aircraft and spray tank ready for BW deployment.  Around 300 people were involved in BW research and development in Iraq. The United Nations weapons inspectors destroyed as much of the BW program as they could find following the end of the Desert Storm. Unfortunately, the Iraqi government did not fully cooperate with UN weapons inspectors and many believed that Iraq still maintained a BW program until 1996 (8, 20, 24, 24, 26).

 South Africa began a covert BW program in 1980 administered by the Surgeon General’s office of the South African Defense Forces (SADF). Front companies were set up to conduct research and development work. The number of BW staff members was small, apparently under 12, with the primary agents of interest being anthrax and cholera.

 Only very small amounts of the BW were prepared and stored. They used their BW in two ways: anthrax was used in assassinations by placing it in food and drink and cholera was placed in wells in areas the SADF was fighting insurgents. The use of BW resulted in minimal insurgent losses. Their BW program did not develop weapon systems or substantial stockpiles. In 1993, after South Africa's involvement in the Angolan war had ended, President de Klerk ordered the destruction of any remaining BW (8, 20).

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Neal Chamberlain, PhD. A. T. Still University of Health Sciences/Kirksville College of Osteopathic Medicine.

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