During the 1948 Israel War of Independence, Red Cross reports raised suspicion that the Jewish Haganah militia had released Salmonella typhi bacteria into the water supply for the city of Acre, causing an outbreak of typhoid among the inhabitants. Egyptian troops later captured disguised Haganah soldiers near wells in Gaza, whom they executed for allegedly attempting another attack. Israel denies these allegations.
During the Cold War, US conscientious objectors were used as consenting test subjects for biological agents in a program known as Operation Whitecoat. There were also many unpublicized tests carried out on the public during the Cold War.
E120 biological bomblet, developed before the U.S. signed the Biological and Toxic Weapons Convention.
Considerable research on the topic was performed by the United States (see US Biological Weapon Testing), the Soviet Union, and probably other major nations throughout the Cold War era, though it is generally believed that biological weapons were never used after World War II. This view was challenged by China and North Korea, who accused the United States of large-scale field testing of biological weapons, including the use of disease-carrying insects against them during the Korean War (1950–1953).
Cuba also accused the US of spreading human and animal disease on their island.  
At the time of the Korean War the US had only weaponized one agent, brucellosis (agent US), which is caused by Brucella suis. The original weaponized form used the M114 bursting bomblet in M33 cluster bombs.
While the specific form of the biological bomb was classified until some years after the Korean War, in the various exhibits of biological weapons that Korea alleged were dropped on their country nothing resembled an M114 bomblet. There were ceramic containers that had some similarity to Japanese weapons used against the Chinese in WWII, developed by Unit 731.
Some of the Unit 731 personnel were imprisoned by the Soviets, and would have been a potential source of information on Japanese weaponization. The head of Unit 731, Lieutenant General Shiro Ishii, was granted immunity from war crimes prosecution in exchange for providing information to the United States on the Unit's activities.
The Korean War allegations also stressed the use of disease vectors, such as fleas, which, again, were probably a legacy of Japanese biological warfare efforts. The United States initiated its weaponization efforts with disease vectors in 1953, focused on Plague-fleas, EEE-mosquitoes, and yellow fever - mosquitoes (OJ-AP). However, US medical scientists in occupied Japan undertook extensive research on insect vectors, with the assistance of former Unit 731 staff, as early as 1946.
The United States Air Force was not satisfied with the operational qualities of the M114/US and labeled it an interim item until the US Army Chemical Corps could deliver a superior weapon. The Air Force also changed its plans and wanted lethal biologicals.
The Chemical Corps then initiated a crash program to weaponize anthrax (N) in the E61 1/2-lb hour-glass bomblet. Though the program was successful in meeting its development goals, the lack of validation on the infectivity of anthrax stalled standardization.
Around 1950 the Chemical Corps also initiated a program to weaponize tularemia (UL). Shortly after the E61/N failed to make standardization, tularemia was standardized in the 3.4" M143 bursting spherical bomblet. This was intended for delivery by the MGM-29 Sergeant missile warhead and could produce 50% infection over a 7-square-mile (18 km2) area.
Unlike anthrax, tularemia had a demonstrated infectivity with human volunteers (Operation Whitecoat). Furthermore, although tularemia is treatable by antibiotics, treatment does not shorten the course of the disease.
In addition to the use of bursting bomblets for creating biological aerosols, the Chemical Corps started investigating aerosol-generating bomblets in the 1950s. The E99 was the first workable design, but was too complex to be manufactured. By the late 1950s the 4.5" E120 spraying spherical bomblet was developed; a B-47 bomber with a SUU-24/A dispenser could infect 50% or more of the population of a 16-square-mile (41 km2) area with tularemia with the E120. The E120 was later superseded by dry-type agents.
Dry-type biologicals resemble talcum powder, and can be disseminated as aerosols using gas expulsion devices instead of a burster or complex sprayer. The Chemical Corps developed Flettner rotor bomblets and later triangular bomblets for wider coverage due to improved glide angles over Magnus-lift spherical bomblets. Weapons of this type were in advanced development by the time the program ended.
Richard Nixon signed an executive order on November 1969, which stopped production of biological weapons in the U.S. and allowed only scientific research of lethal biological agents and defensive measures such as immunization and biosafety. The biological munition stockpiles were destroyed, and approximately 2,200 researchers became redundant.
United States special forces and the CIA also had an interest in biological warfare, and a series of special munitions was created for their operations. The covert weapons developed for the military (M1, M2, M4, M5, and M32 - or Big Five Weapons) were destroyed in accordance with Nixon's executive order to end the offensive program. The CIA maintained its collection of biologicals well into 1975 when it became the subject of the senate Church Committee.
The Biological Weapons Convention
In 1972, the U.S. signed the Biological and Toxic Weapons Convention, which banned the "development, production and stockpiling of microbes or their poisonous products except in amounts necessary for protective and peaceful research." By 1996, 137 countries had signed the treaty; however it is believed that since the signing of the Convention the number of countries capable of producing such weapons has increased.
The Soviet Union continued research and production of offensive biological weapons in a program called Biopreparat, despite having signed the convention. The United States was unaware of the program until Dr. Vladimir Pasechnik defected in 1989, and Dr. Kanatjan Alibekov, the first deputy director of Biopreparat defected in 1992.
After the 1991 Persian Gulf War, Iraq admitted to the United Nations inspection team to having produced 19,000 L of concentrated botulinum toxin, of which approximately 10,000 L were loaded into military weapons; the 19,000 L have never been fully accounted for. This is approximately 3 times the amount needed to kill the entire current human population by inhalation, although in practice it would be impossible to distribute it so efficiently, and, unless it is protected from oxygen, it deteriorates in storage.
On September 18, 2001 and for a few days after several letters were received by members of the U.S. Congress and media outlets containing anthrax spores: the attack killed five people. The identity of the perpetrator remained unknown until 2008, when a primary suspect was named. See 2001 anthrax attacks.
Main article: Biological agent
Biological warfare is the deliberate use of disease and natural poisons to incapacitate humans. It employs pathogens as weapons. Pathogens are the micro-organism, whether bacterial, viral or protozoic, that cause disease. There are four kinds of biological warfare agents: bacteria, viruses, protists, and fungi. Biological weapons are distinguished by being living organisms, that reproduce within their host victims, who then become contagious with a deadly, if weakening, multiplier effect. Toxins in contrast do not reproduce in the victim and need only the briefest of incubation periods; they kill within a few hours.
Biological weapons characteristics
 Anti-personnel BW
The international biological hazard symbol.
Ideal characteristics of biological weapons targeting humans are high infectivity, high potency, non-availability of vaccines, and delivery as an aerosol.
Diseases most likely to be considered for use as biological weapons are contenders because of their lethality (if delivered efficiently), and robustness (making aerosol delivery feasible).
The biological agents used in biological weapons can often be manufactured quickly and easily. The primary difficulty is not the production of the biological agent but delivery in an effective form to a vulnerable target.
For example, anthrax is considered an effective agent for several reasons. First, it forms hardy spores, perfect for dispersal aerosols. Second, pneumonic (lung) infections of anthrax usually do not cause secondary infections in other people. Thus, the effect of the agent is usually confined to the target. A pneumonic anthrax infection starts with ordinary "cold" symptoms and quickly becomes lethal, with a fatality rate that is 90% or higher. Finally, friendly personnel can be protected with suitable antibiotics.
A mass attack using anthrax would require the creation of aerosol particles of 1.5 to 5 micrometres. Too large and the aerosol would be filtered out by the respiratory system. Too small and the aerosol would be inhaled and exhaled. Also, at this size, nonconductive powders tend to clump and cling because of electrostatic charges. This hinders dispersion. So the material must be treated to insulate and discharge the charges. The aerosol must be delivered so that rain and sun does not rot it, and yet the human lung can be infected. There are other technological difficulties as well.
Diseases considered for weaponization, or known to be weaponized, include anthrax, ebola, Marburg virus, plague, cholera, tularemia, brucellosis, Q fever, Bolivian hemorrhagic fever, Coccidioides mycosis, glanders, Melioidosis, Shigella, Rocky Mountain spotted fever, typhus, Psittacosis, yellow fever, Japanese B encephalitis, Rift Valley fever, and smallpox . Naturally-occurring toxins that can be used as weapons include ricin, SEB, botulism toxin, saxitoxin, and many mycotoxins. The organisms causing these diseases are known as select agents. In the United States, their possession, use, and transfer are regulated by the Centers for Disease Control and Prevention's Select Agent Program.
Biological warfare can also specifically target plants to destroy crops or defoliate vegetation. The United States and Britain discovered plant growth regulators (i.e., herbicides) during the Second World War, and initiated an herbicidal warfare program that was eventually used in Malaya and Vietnam in counter insurgency. Though herbicides are chemicals, they are often grouped with biological warfare as bioregulators in a similar manner as biotoxins. Scorched earth tactics or destroying livestock and farmland were carried out in the Vietnam war (cf. Agent Orange) and Eelam War in Sri Lanka.
The United States developed an anti-crop capability during the Cold War that used plant diseases (bioherbicides, or mycoherbicides) for destroying enemy agriculture. It was believed that destruction of enemy agriculture on a strategic scale could thwart Sino-Soviet aggression in a general war. Diseases such as wheat blast and rice blast were weaponized in aerial spray tanks and cluster bombs for delivery to enemy water sheds in agricultural regions to initiate epiphytotics (epidemics among plants). When the United States renounced its offensive biological warfare program in 1969 and 1970, the vast majority of its biological arsenal was composed of these plant diseases.
In 1980s Soviet Ministry of Agriculture had successfully developed variants of foot-and-mouth disease, and rinderpest against cows, African swine fever for pigs, and psittacosis to kill chicken. These agents were prepared to spray them down from tanks attached to airplanes over hundreds of miles. The secret program was code-named "Ecology".
Attacking animals is another area of biological warfare intended to eliminate animal resources for transportation and food. In the First World War, German agents were arrested attempting to inoculate draft animals with anthrax, and they were believed to be responsible for outbreaks of glanders in horses and mules. The British tainted small feed cakes with anthrax in the Second World War as a potential means of attacking German cattle for food denial, but never employed the weapon. In the 1950s, the United States had a field trial with hog cholera. During the Mau Mau Uprising in 1952, the poisonous latex of the African milk bush was used to kill cattle.
Unconnected with inter-human wars, humans have deliberately introduced the rabbit disease Myxomatosis, originating in South America, to Australia and Europe, with the intention of reducing the rabbit population - which had devastating but temporary results, with wild rabbit populations reduced to a fraction of their former size but survivors developing immunity and increasing again.
Main article: Biodefense
 Role of public health departments and disease surveillance
It is important to note that all of the classical and modern biological weapons organisms are animal diseases, the only exception being smallpox. Thus, in any use of biological weapons, it is highly likely that animals will become ill either simultaneously with, or perhaps earlier than humans.
Indeed, in the largest biological weapons accident known– the anthrax outbreak in Sverdlovsk (now Yekaterinburg) in the Soviet Union in 1979, sheep became ill with anthrax as far as 200 kilometers from the release point of the organism from a military facility in the southeastern portion of the city (known as Compound 19 and still off limits to visitors today, see Sverdlovsk Anthrax leak).
Thus, a robust surveillance system involving human clinicians and veterinarians may identify a bioweapons attack early in the course of an epidemic, permitting the prophylaxis of disease in the vast majority of people (and/or animals) exposed but not yet ill.
For example in the case of anthrax, it is likely that by 24 – 36 hours after an attack, some small percentage of individuals (those with compromised immune system or who had received a large dose of the organism due to proximity to the release point) will become ill with classical symptoms and signs (including a virtually unique chest X-ray finding, often recognized by public health officials if they receive timely reports). By making these data available to local public health officials in real time, most models of anthrax epidemics indicate that more than 80% of an exposed population can receive antibiotic treatment before becoming symptomatic, and thus avoid the moderately high mortality of the disease.
Identification of bioweapons
The goal of biodefense is to integrate the sustained efforts of the national and homeland security, medical, public health, intelligence, diplomatic, and law enforcement communities. Health care providers and public health officers are among the first lines of defense. In some countries private, local, and provincial (state) capabilities are being augmented by and coordinated with federal assets, to provide layered defenses against biological weapons attacks. During the first Gulf War the United Nations activated a biological and chemical response team, Task Force Scorpio, to respond to any potential use of weapons of mass destruction on civilians.
The traditional approach toward protecting agriculture, food, and water: focusing on the natural or unintentional introduction of a disease is being strengthened by focused efforts to address current and anticipated future biological weapons threats that may be deliberate, multiple, and repetitive.
The growing threat of biowarfare agents and bioterrorism has led to the development of specific field tools that perform on-the-spot analysis and identification of encountered suspect materials. One such technology, being developed by researchers from the Lawrence Livermore National Laboratory (LLNL), employs a "sandwich immunoassay", in which fluorescent dye-labeled antibodies aimed at specific pathogens are attached to silver and gold nanowires. 
In the Netherlands, the company TNO has designed Bioaerosol Single Particle Recognition eQuipment (BiosparQ). This system would be implemented into the national response plan for bioweapons attacks in the Netherlands.
Researchers at Ben Gurion University in Israel are developing a different device called the BioPen, essentially a "Lab-in-a-Pen", which can detect known biological agents in under 20 minutes using an adaptation of the ELISA, a similar widely employed immunological technique, that in this case incorporates fiber optics. 
List of BW institutions and programs by country
According to the United States Office of Technology Assessment, since disbanded, seventeen countries were believed to possess biological weapons in 1995: Libya, North Korea, South Korea, Iraq, Taiwan, Syria, Israel, Iran, China, Egypt, Vietnam, Laos, Cuba, Bulgaria, India, South Africa, and Russia.
Main article: United States biological weapons program
Fort Detrick, Maryland
U.S. Army Biological Warfare Laboratories (1943–69)
One-Million-Liter Test Sphere
United States Army Medical Unit (1954–69)
U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID; 1969–present)
National Biodefense Analysis and Countermeasures Center (NBACC; Projected: 2008)
Project Clear Vision