Biological weapons are weapons based on infection caused by live microorganisms such as bacteria and viruses, and the term is also usually used to include weapons based on toxins – toxic chemicals produced naturally by organisms that can be used as a crude or purified preparation to cause disease among people or animals. Many microorganisms are harmless, and those that cause disease are known as pathogens. We use the term ‘biological agent’ to mean those pathogens which in principle can be used as biological weapons.
Most biological warfare agents are ubiquitous in the natural environment; they can be found in water, soil, plants and animals. Most agents reproduce rapidly and require minimal resources for preservation. Some biological agents are very dangerous because they are easy to disperse, stable and infectious even in miniscule doses – as few as a few organisms. Many can be aerosolised as an effective method of delivery. Some diseases can cause extremely serious population effects because they can spread so easily from person to person, animal to animal etc. Most pathogens ‘die’ quite rapidly in the environment, within hours or days; but a few, notably anthrax spores, can persist and remain infectious for years, creating long term decontamination issues.
Biological warfare dates back to antiquity and has been practiced ever since. There are many historic examples of deliberate use of disease, such as poisoning of food and water with infectious material, spreading disease by means of infected animals or animal carcasses, contaminated clothing, etc.
The 20th Century World Wars had a huge impact on the systematic development of biological weapons, in parallel with great advances in knowledge about how infections are caused and how to produce microorganisms including pathogens in the laboratory and on larger scales. Throughout the First World War, the German army had a programme to weaponise the agents causing anthrax, glanders, cholera, as well as a wheat fungus. Even before World War II, Japanese forces operated a secret biological warfare research facility that carried out experiments on prisoners and was involved in attacks on civilian populations and troops in the war with China. During WW II the United States had a programme to investigate the use of anthrax and botulinum toxin as a weapon and the British tested anthrax bombs and prepared and stockpiled anthrax-laced cattle cakes. The United States continued major R&D and procurement programmes for biological weapons during the 1950s and 1960s, and the Soviet Union programme continued even later.
Today, a small number of countries are alleged to have biological weapons offensive research programmes in spite of the opprobrium of the 1972 Biological Weapons Convention (BWC) which prohibits the development and acquisition of these weapons. Additionally, terrorist organisations and individuals might also have an interest in the use of biological agents in order to spread fear and disrupt society. Of greatest threat are those organisations that are well funded and possibly state-supported. It is most likely that they have access to scientific expertise to produce, store and weaponise biological agents.
Bacteria
Bacteria are single cell micro-organisms which reproduce rapidly in the host or even in quite simple artificial media, allowing production in a laboratory or on an industrial scale.
Rickettsiae
Rickettsiae are bacteria like organisms, much smaller than a bacterium and therefore able to pass through bacterial filters.
Toxins
Toxins are among the most toxic chemicals known. They are produced by microorganisms or higher organisms such as spiders and snakes (the venoms) or can be extracted from plants (e.g. the mycotoxins).
Viruses
Viruses consist of genetic material (DNA or RNA) surrounded by a protective coat of protein. Viruses cannot multiply on their own: they need to invade the cells of a host in order to reproduce.