Molecular Assassins: The History and Impact of Bio-weapons

1.0 Introduction

During the past century, infectious diseases have exacted a staggering toll, claiming over 500 million lives. Among these casualties, tens of thousands were victims of deliberate pathogen releases. Notably by the Japanese during their assaults on China in World War II [Source]. The World Health Organization (WHO) defines biological weapons, also known as bio-weapons or unconventional weapons, as deliberate releases of microorganisms like viruses, bacteria, or fungi, or toxic substances produced by living organisms, intending to cause disease and death in humans, animals, or plants. [Source]

Despite treaties in 1925 and 1972 outlawing biological weapons, states persist in researching and producing these lethal agents. This persistence is fuelled by advancements in understanding disease and historical pandemics, fuelling fears of modified pathogens for biological warfare. Today, organisations like WHO deploy Global Outbreak Alert and Response Network (GOARN) to detect and contain biological agent releases. This network is deployed with the affected state’s consent to provide an interagency solution in case of a biological attack. In this article, we explore the shadowy history and impacts of biological weapons, tracing their evolution from ancient times to modern conflicts. We explore key figures, components, and future trajectories, shedding light on the threats posed by the weapons. 

2. History of Bio-weapons

The history of biological warfare is as old as conflict itself. Ancient civilisations such as the Assyrians and Greeks employed crude methods of biological warfare. These methods included using animal carcasses to contaminate enemy water supplies [Source]. However, it was not until the modern era that bio-weapons became more systematically developed and deployed. The advent of microbiology in the 19th century further sped up the development of bio-weapons. Despite early prohibitions on poisoned weapons, nations continued to explore biological warfare capabilities. Particularly during World War I and its aftermath. The Japanese, under the leadership of Shiro Ishii, conducted large-scale bio-weapons research during World War II. Research methods included releasing deadly agents on Chinese civilians and prisoners of war [Source].

2.1 Japan and Unit 731

During World War II, Japan established a notorious biological weapons program, known as Unit 731, which conducted extensive research and experimentation. The program’s operations resulted in the development and deployment of lethal pathogens, including anthrax, plague, and cholera, among others. According to historical records, Unit 731 subjected over 3,000 prisoners to inhumane experiments, often leading to excruciating deaths. The program peaked in the late 1930s and early 1940s, with facilities across occupied territories in China and Southeast Asia. Estimates suggest these bio-weapons caused the deaths of at least tens of thousands of civilians and soldiers during the war. Despite secrecy, investigations revealed atrocities under the guise of research, highlighting Japan’s devastating pursuit of biological warfare [Source], [Source].

2.2 US Bio-weapon Program

A drill simulating a mass casualty event onboard the USS Ronald Reagan. Source: (US Navy Institute)

Post WWI, the United States initiated its own bio-weapons research intending to research and develop the toxin ricin. In the 1940s, the US aimed to expand its bio-weapons programs and aimed to develop offensive and defensive bio-weapons. After WWII, the US used Japanese bio-weapon research conducted by Unit 731 to bolster its program. The US granted immunity to Unit 731 researchers in exchange for their information on developing such weapons. US research teams conducted open-air tests exposing civilians to pathogens, including the infamous New York metro system contamination in 1966. However, growing opposition to biological weapons, coupled with the fear of their accessibility as “poor man’s nuclear bombs,” led President Nixon to abandon offensive research and sign the Biological and Toxin Weapons Convention in 1972 [Source], [Source]. 


The biological weapons factory in Stepnogorsk, Kazakhstan, where the Soviet Union stood ready to manufacture tons of anthrax upon directives from Moscow. (Source: National Security Archive)
The biological weapons factory in Kazakhstan where the Soviet Union stood ready to manufacture tons of anthrax upon directives from Moscow. (Source: National Security Archive)

The Soviet Union’s bio-weapons program under Biopreparat was one of the largest and most clandestine in history. It spanned several decades throughout the Cold War era. Besides employing over 50,000 personnel, the program operated many research facilities and production sites across the Soviet Union. Biopreparat explored genetically engineered pathogens for military use, beyond stockpiling deadly agents like anthrax and smallpox. The program suffered from accidents and mishaps, with notable incidents including the accidental release of anthrax spores in the city of Sverdlovsk in 1979, resulting in dozens of fatalities. Moreover, the collapse of the Soviet Union in 1991 revealed the extent of the bio-weapons program, raising concerns about the security of remaining bio-weapons stockpiles and expertise proliferation [Source], [Source].

2.0 Biological Explanation

Biological weapons harness microorganisms and toxins to cause disease and death in humans, animals, or plants. These weapons exploit the unique characteristics of biological agents, such as bacteria, viruses, fungi, or toxins derived from living organisms, to inflict harm on targeted populations. The biological nature of these weapons often renders them invisible, odourless, and tasteless, making detection and defence challenging. Furthermore, biological agents can be engineered or modified to enhance their virulence, resistance to treatment, or ability to evade detection, amplifying their destructive potential. For instance, individuals have weaponized pathogens like anthrax, botulinum toxin, and the smallpox virus due to their ability to cause severe illness or death in relatively small quantities. [Source].

According to the Centers for Disease Control and Prevention (CDC), a single gram of weaponized anthrax spores, if efficiently dispersed, could theoretically infect up to 1 million people. Similarly, the World Health Organization (WHO) estimates that the deliberate release of the smallpox virus could lead to a global pandemic, with catastrophic casualties and societal disruption. Moreover, the rapid spread of infectious diseases in an interconnected world exacerbates the risk posed by biological weapons, as showed by recent pandemics such as COVID-19 [Source],[Source]. 

2.1 Categories of Biological Agents

The Centers for Disease Control and Prevention (CDC) lists 35 agents as potential bio-weapons. They classify the agents into three categories: Category A, B and C according to the danger they pose, and the possibility of the pathogens being engineered for mass dispersion. The three conditions they consider in their classifications are “availability, ease of production and dissemination and potential for high morbidity”.

2.1.1 Category A Agents

These agents can cause massive public fear and civil disruption, requiring the highest level of public health preparedness. [Source]

  • Anthrax (Bacillus anthracis): Inhalation, ingestion, or skin contact with anthrax bacteria can lead to severe infection. Anthrax has an estimated mortality rate of up to 95%, particularly if not treated promptly. Symptoms typically include flu-like symptoms such as fever, chills, sweats, and malaise. These symptoms can also progress to severe respiratory distress, meningitis, and sepsis [Source].
  • Smallpox (Variola virus): Smallpox is a highly contagious viral disease with a mortality rate of approximately 30%. Initial symptoms include fever, malaise, and prostration, followed by the development of characteristic skin lesions. Smallpox vaccination ceased in 1972, leaving populations born afterwards vulnerable to the disease [Source].
  • Plague (Yersinia pestis): Plague can manifest in various forms, including bubonic, pneumonic, and septicemic plague. Pneumonic plague, which spreads through aerosolized droplets, has the highest mortality rate of up to 100% if untreated. Symptoms include fever, bloody or watery mucus, and respiratory failure [Source].
  • Botulinum Toxin: Botulinum toxin, produced by Clostridium botulinum bacteria, is one of the most potent toxins known. It causes paralysis by blocking nerve signals to muscles. Symptoms of botulism include droopy eyelids, muscle weakness, and difficulty breathing. Without prompt treatment, botulism can be fatal [Source].
  • Tularemia (Francisella tularensis): Tularemia is caused by the bacterium Francisella tularensis and can spread through inhalation, ingestion, or contact with infected animals or environments. Symptoms typically appear 3-5 days after exposure and may include fever, swollen lymph nodes, and respiratory symptoms [Source].
  • Viral Hemorrhagic Fevers: This category includes several viruses such as Ebola virus, Marburg virus, and Lassa virus. Viral hemorrhagic fevers can cause severe illness with symptoms including fever, bleeding, and organ failure. Mortality rates vary, with some strains having mortality rates as high as 90% [Source].

2.1.2 Category B Agents

While not as immediately lethal or contagious as Category A agents, Category B biological weapons still pose significant risks to public health and safety. These agents have the potential for dissemination and can cause illness, with fewer incidents and lower mortality rates compared to Category A agents. [Source]

  • Q fever: Caused by the bacterium Coxiella burneti, Q fever can cause flu-like symptoms and, in severe cases, pneumonia or hepatitis.Infected animals or contaminated environments can transmit the bacterium through contact. [Source].
  • Brucella species: Brucellosis, caused by bacteria of the Brucella genus, leads to symptoms such as fever, muscle pain, and fatigue. The disease primarily affects animals but can be transmitted to humans through the consumption of contaminated dairy products or through direct contact with infected animals [Source].
  • Ricin: Ricin is a highly toxic protein derived from castor beans. It can cause severe organ damage and death if ingested, inhaled, or injected. Ricin poisoning leads to symptoms such as nausea, vomiting, diarrhoea, and respiratory distress. There is currently no antidote for ricin poisoning [Source].
  • Burkholderia Mallei: This bacterium causes glanders, a disease primarily affecting horses, donkeys, and mules. In humans, glanders can lead to symptoms such as fever, pneumonia, and skin lesions. The bacterium can be transmitted through direct contact with infected animals or inhalation of contaminated aerosols [Source].
  • Alphaviruses: Alphaviruses like Venezuelan equine encephalitis virus (VEEV) and Eastern equine encephalitis virus (EEEV) can cause encephalitis in humans. Symptoms include fever, headache, and neurological complications. Mosquitoes primarily transmit these viruses. [Source].
  • Vibrio cholerae: Cholera, caused by Vibrio cholerae bacteria, leads to profuse watery diarrhoea and dehydration. The disease can spread rapidly in areas with poor sanitation and contaminated water sources [Source].

The agents listed above are among the 12 agents/diseases classified in this category by the CDC.

2.1.3 Category C Agents

Category C agents are not considered as immediate of a threat as Category A or B agents, but they still possess the potential to be developed into bio-weapons with advances in scientific understanding. The CDC categorises Nipah and Hanta virus as category C agents [Source]

Hantavirus: Hantavirus infections can cause Hantavirus pulmonary syndrome (HPS) or haemorrhagic fever with renal syndrome (HFRS), depending on the virus strain. Symptoms range from flu-like illness to severe respiratory or kidney failure [Source].

[Source] [Source] [Source]

Japan had a covert biological and chemical warfare research unit during World War II.

3.0 Key Figures in bio-weapons

Key figures who played pivotal roles in the development, research, and proliferation of biological weapons intertwined the history of these weapons. One such figure is Shiro Ishii, a Japanese microbiologist and army officer who led Unit 731, a covert biological and chemical warfare research unit during World War II. Under Ishii’s leadership, Unit 731 conducted gruesome experiments on prisoners of war and civilians. They researched methods of weaponizing deadly pathogens like anthrax, plague, and cholera. Ishii’s unethical actions resulted in the suffering and deaths of thousands, leaving a dark legacy of human experimentation and biological warfare atrocities [Source], [Source].

Vladimir Pasechnik

Another significant figure in the history of biological weapons is Vladimir Pasechnik, a Soviet microbiologist who defected to the West in 1989. Pasechnik played a key role in the Soviet Union’s bioweapons program, particularly in the development of genetically modified pathogens. Following his defection, Pasechnik provided valuable insights into the extent and capabilities of the Soviet bioweapons program, shedding light on the clandestine activities and research conducted by Biopreparat, the Soviet agency tasked with biological warfare research and production. Pasechnik’s revelations contributed to international efforts to address the threat posed by biological weapons proliferation [Source], [Source].

Ken Alibek

Dr. Ken Alibek (formerly known as Kanatjan Alibekov) is a prominent figure in the history of biological weapons. He was involved in the Soviet bioweapons program and defected to the United States in 1992. Alibek held high-ranking positions within Biopreparat and played a crucial role in developing and producing biological weapons, including anthrax and plague. Following his defection, Alibek provided valuable intelligence on the Soviet bioweapons program. He offered insights into its organizational structure, research activities, and capabilities. Alibek’s defection and disclosures contributed to international efforts to counter biological weapons proliferation and strengthen global biosecurity measures. [Source], [Source].

George W. Merck

In the US history of biological weapons development, several key figures played significant roles in research, policymaking, and disarmament efforts. One notable figure is Dr. George W. Merck, an American pharmaceutical executive who contributed to the U.S. biological warfare program during World War II. Merck served as the head of the War Research Service’s Division of Biological and Chemical Warfare at Fort Detrick, Maryland. Under his leadership, the division conducted research on biological agents and developed methods for their production and dissemination [Source].

William C. Patrick

Another influential figure in the U.S. biological weapons program is Dr. William C. Patrick III, a microbiologist and former bioweapons expert at Fort Detrick. Patrick played a central role in the development and testing of biological weapons for the U.S. military during the Cold War era. He was instrumental in designing delivery systems for biological agents, including bombs, rockets, and spray devices, as well as developing techniques for agent stabilization and dissemination. Patrick’s expertise contributed to the advancement of the U.S. bioweapons program and its capabilities for offensive biological warfare [Source].

David Franz

Furthermore, Dr. David Franz emerges as a key figure in the history of U.S. biological weapons due to his involvement in both offensive and defensive biowarfare research. Franz served as the commander of the U.S. Army Medical Research Institute of Infectious Diseases (USAMRIID) at Fort Detrick, where he oversaw research on biological agents and their potential use as weapons. Following his military career, Franz became a leading advocate for biodefense and biosecurity, promoting measures to prevent the proliferation of biological weapons and mitigate the risks posed by bioterrorism. His contributions to the field have shaped U.S. policy and preparedness efforts in confronting the threat of biological warfare [Source].

3.1 Proliferation of bio-weapons 

The earliest recorded instance of modern bioweapon uses during World War I led to the signing of the Geneva Protocol in 1925. The protocol prohibited the use of biological and chemical weapons in warfare; however, it did not ban their development or stockpiling [Source].

Despite the Geneva Protocol, concerns over bioweapons continued to grow throughout the 20th century, particularly during the Cold War era. The Biological Weapons Convention (BWC) of 1972 was a landmark international treaty aimed at prohibiting the development, production, and stockpiling of biological weapons. Over 180 countries are now signatories to the BWC, including major powers like the United States, Russia, and China. International organizations like WHO and UN monitor BWC compliance and promote global health security against bioweapon proliferation and use. Despite these efforts, concerns persist regarding the potential for rogue states or terrorist organizations to acquire and utilize bioweapons, highlighting the ongoing importance of international cooperation and vigilance in preventing their proliferation [Source].

The BWC does not have a formal verification mechanism but relies on transparency and consultations among its member states to ensure compliance. Despite fostering global norms against biological weapons, the BWC faces challenges in enforcement and verification, especially with emerging biotechnologies and non-state actors’ potential use. Efforts to strengthen the BWC and address bioweapons proliferation involve conferences, workshops, and cooperation among member states and international organizations. However, there hasn’t been a more recent treaty specifically focused on the proliferation of bioweapons since the BWC [Source].

4.0 Future Trajectories

CBIRF Marines monitor UGV 'Cerberus' detecting hazards during Technology Experimentation and Characterization Field Trials at CBIRF Downey Responder Training Facility, cohosted by Naval Surface Warfare Center Indian Head Division. Source: U.S. Navy

Biological weapons pose significant challenges and uncertainties, driven by evolving technologies, geopolitical tensions, and emerging threats. Advances in biotechnology, like CRISPR-Cas9 gene editing, raise concerns about creating more precise and lethal biological weapons. Biotechnology merging with AI and nanotechnology could improve biological weapons with targeted delivery, detection evasion, and autonomous decision-making. AI has vast potential to speed up biological weapon development and deployment through data analysis, predictive modeling, and autonomous systems. However, AI also offers opportunities for enhancing biosecurity and biosafety measures, including the use of AI-driven surveillance systems for early detection of infectious disease outbreaks and monitoring of biodefense facilities. As AI continues to advance, its impact on the proliferation and mitigation of biological threats will become increasingly significant, requiring proactive strategies and international cooperation to navigate the complex intersection of AI and bioweapons.

Geopolitical tensions and the proliferation of dual-use technologies increase the likelihood of state and non-state actors acquiring biological weapons capabilities. As seen in recent years, geopolitical rivalries and conflicts have led to suspicions of bioweapons development and use, heightening global security concerns.Emerging infectious diseases, zoonotic spillover events, and pandemics highlight the importance of preparedness and response to mitigate risks from both natural and deliberate biological threats. To address these challenges, international cooperation and multilateral frameworks will be essential in strengthening biosecurity, biosafety, and non-proliferation efforts. Improved surveillance and early warning systems, coupled with rapid response capabilities, are crucial for detecting and containing outbreaks of infectious diseases and potential bioweapons incidents. 

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