Biological warfare: what you need to know
Biological weapons may seem a relatively recent feature on the landscape of war, but deadly biological agents, be they bacteria, viruses or poisons from plants, and the methods of spreading them effectively, have been a focus of military strategists and terrorists for many years.
As far back as the 1760s, even the British weren’t above a bit of viral warfare, deliberately introducing smallpox in their bid to exterminate the native peoples of North America. Blankets from the local smallpox hospital were proferred as a gift to the ‘Indians’. The resulting outbreak of smallpox killed more than half of the local native population.
The agents of disease may not have changed much, but the methods of delivery have become more sophisticated. Here, we take a look at the agents believed to pose the biggest threat and how they might be spread.
The biological threat
The development of bioweapons and the capability to produce large enough quantities of biological agents for war carried on throughout the twentieth century. In 1972 the Biological Weapons Convention was signed by more than 100 countries, including the USA, which, by 1973, along with most other countries, had destroyed its biological weapons. By the end of 2002, 146 countries had signed the Biological Weapons Convention.
Following the September 11, 2001, terrorist attacks in the USA, governments and health authorities worldwide have honed and developed their contingency plans for dealing with bioterrorist attacks. Possible biological agents have been stratified according to their risk and potential for spreading disease and causing death.
Successful bioweapons
While there are many poisonous or deadly infections, not all lend themselves to being used as agents of war. Some key features of a successful bioweapon agent are that it:
- can be spread from person to person easily;
- results in a high death rate;
- would cause public panic;
- would require special action from public health authorities for them to be prepared; and
- has no easily available treatment, vaccine or antidote.
Methods of delivery
The method used to deliver bacteria or viruses as a bioweapon would depend on the particular organism and its characteristics. People could become infected by breathing in droplets infected with the organism (as an aerosol), through their skin, by eating contaminated food or drinking contaminated water. Spores of an organism like anthrax, that can survive in a dormant state for decades in suitable soil, could be spread through the air and remain in soil as a source of possible infection.
The methods most often feared for biological warfare are the aerosolisation of large quantities of organisms or spores over a densely populated area by detonating a weapon, or the widespread contamination of food or drinking water supplies with deadly organisms or poisons.
The agents
Here are some of the agents that have been identified worldwide as posing the greatest potential threat.
| Biological warfare agents | ||||
|---|---|---|---|---|
| Disease or poison | Microbe causing the disease | Method of transmission or delivery | Symptoms | Antidote or treatment |
| Anthrax | Bacillus anthracis bacterium |
Inhalation; through the skin; or eating contaminated food. Person to person transmission unlikely. Humans usually infected by direct contact with infected animals or animal products. |
Usually within 7 days. Inhalational anthrax starts like a common cold, progresses to severe breathing problems and shock. Cutaneous (skin) anthrax starts as small red swellings which develop into black depressions. |
Antibiotics. Must be given early in infection. A vaccine exists in USA. |
| Smallpox | Variola virus | Close and lengthy face-to-face contact; via infected body fluids; or via contaminated objects, such as bedding. | High fever, headache, and body ache, followed in 2-4 days by initial rash. Followed by characteristic pustular bumps. | Vaccine, although heart inflammation has been reported as a side-effect. |
| Plague | Yersinia pestis bacterium |
Naturally occurring plague: plague infected fleas leave their animal host (e.g. rat) and bite humans (bubonic plague). Biological warfare: aerosols of Y. pestis bacteria would be released, causing pneumonic plague which is transmitted by breathing in the bacteria. |
Naturally occurring plague: Swollen, tender lymph nodes; fever, chills; and weakness. Biological warfare: Fever; headache; weakness; pneumonia; chest pain; and cough progressing to respiratory failure. |
Antibiotics. No vaccine. Surgical mask to protect against infection. |
| Tularaemia | Francisella tularensis bacterium |
Bites of infected ticks and flies; handling infected animals; inhalation; or eating or drinking contaminated food or water. Person to person transmission unknown. |
If inhaled: fever, ache, cough and weakness. Respiratory illness progressing to pneumonia. | Antibiotics. Vaccine was developed in USA, but may have been withdrawn. |
| Botulism | Clostridium botulinum bacterium |
Foodborne botulism and infant botulism: eating food contaminated with toxin or spores. Wound botulism: infecting wound with soil or other material containing botulinum spores or bacteria. Injecting street drugs increases risk of wound botulism. No person to person transmission. |
Vision problems: double or blurred vision; and drooping eyelids. Muscle weakness; swallowing difficulties; dry mouth; and slurred speech. Infants seem lethargic, floppy, constipated, and off food. Adults and children progress to paralysis of limbs and breathing muscles. |
Artificial ventilation may be needed for respiratory failure. Antitoxin must be given early. Surgery for infected wounds. Long-term medical care for recovery. |
| Viral haemorrhagic fevers (VHFs) | These include Ebola virus; Marburg virus, Lassa virus, yellow fever virus; and Rift Valley fever virus. |
Bite of infected insect; inhaling infected rodent droppings; or contact with carcass of infected animal. Person to person transmission for most of the VHFs, but not others, such as Rift Valley and yellow fevers. |
Fever; headache; muscle and joint aches; and skin flushing or rash. Later, haemorrhage in skin and eyes; delirium; convulsions; shock and coma. | Treatment limited to high maintenance medical support. No approved drug. Yellow fever is the only VHF with a vaccine. |
| Ricin | None. It’s a poison made from seeds of castor bean. | Injection; swallowing; or breathing in mist or powder. |
Injection: muscles and lymph nodes die; bleeding from stomach and intestines; and multi-organ failure. Swallowing: internal bleeding; vomiting and bloody diarrhoea; and multi-organ failure. Breathing in: Coughing; hot lungs; breathing difficulties; and fluid in lungs. |
No antidote. Supportive medical care. |
Anthrax
The anthrax bacterium does not survive long outside of its human or animal host, but anthrax spores can survive for decades in soil. The British experimented with bombs loaded with anthrax spores in the 1940s on the remote Scottish island of Gruinard. Forty years later, the island was still contaminated with viable spores and had to be decontaminated with great effort.
In 2001, anthrax spores were mailed via the US Postal Service and infected 22 people: 11 with inhalational anthrax; and 11 with cutaneous anthrax. Five of the people with inhalational anthrax died.
As well as this direct contamination with spores, another method of attack using anthrax could be to make an aerosol release of spores over a densely populated area. The spores don’t smell and being microscopic can’t be seen. They could travel on the wind to other locations, too.
Anthrax responds to antibiotics given early in the infection, but it’s possible that strains of the bacterium could be developed that are resistant to the antibiotics usually used to treat it.
Smallpox
Smallpox was eradicated worldwide in 1977 by a World Health Organization (WHO) campaign. The last known naturally occurring case was in Somalia in 1977. But the smallpox virus lives on in 2 highly secure WHO reference laboratories in the USA and Russia, and also possibly in the arsenal of any country that didn’t comply with the WHO recommendation to destroy all stocks of the virus. Widespread vaccination was stopped after the virus was eradicated, but in the US large numbers of people have been vaccinated as recently as 2002 and 2003, including civilians and troops serving in Iraq, so it’s still regarded as a potential threat as a biological weapon.
Plague
Plague has been around for centuries: the Black Death killed a third of Europe’s population in the 1300s. Its spread was unrelenting, carried by rats and humans from settlement to settlement. Fleas infected by plague lived on the rats and then moved to humans. The people bitten by infected fleas developed bubonic plague.
Australia is said to be the only populated continent without an animal reservoir of plague. Ground squirrels, rats and other rodents on the other continents provide a reservoir for the less than 2000 natural cases that occur every year in humans.
A more recent plague epidemic started in the Manchuria region of China during World War II, after the Japanese reportedly dropped plague-infected fleas from aircraft onto the populated region.
Since then, biological weapons programmes have eliminated the need for the flea and, nowadays, a bioterrorist attack using plague would probably be via the aerosol method, with the people infected getting pneumonic, rather than bubonic, plague. Antibiotics need to be given in the first 24 hours to reduce the chance of death.
Tularaemia
The tularaemia bacterium is one of the most infectious disease-causing bacteria known. For this reason it has been studied as a biological weapon and was probably used in World War II on the Eastern European front, when there were large outbreaks among German and Soviet troops.
The bacterium can live in soil, water and in voles, mice, rabbits and other mammals. Humans catch tularaemia from bites of infected ticks and flies, or from food and water, or by breathing in infected aerosols.
Botulism
Botulinum toxin is a highly poisonous nerve toxin produced by the Clostridium botulinum bacterium. We know it more commonly as ‘botox’ — and because of its muscle paralysing properties it is used in cosmetic injections to ‘relax’ (paralyse) the muscles of the forehead.
Botulinum toxin’s ability to relax muscles can also be harnessed for more serious medical uses, such as relaxing muscles in cerebral palsy and in facial nerve disorders. However, when this same muscle relaxing ability is applied to the breathing muscles, as happens in the course of a botulism infection, then respiratory failure and death will result.
There are 3 kinds of botulism infections: foodborne botulism; infant botulism; and wound botulism. If not treated, they can all progress to cause paralysis of the limbs and the breathing muscles, leading to respiratory failure and death. Even with treatment such as antitoxin, recovery from botulism takes months and the person may have to be on a ventilator to help them breathe during this time.
The haemorrhagic fevers
The haemorrhagic fevers are caused by viruses which include Ebola and Marburg viruses, Rift Valley fever, Lassa fever and yellow fever viruses.
The haemorrhagic fever viruses attack all systems of the body. The damage to the vascular (blood) system usually results in bleeding under the skin (haemorrhage), hence the name haemorrhagic fever. The viruses can show different symptoms and not all infected people will show the same signs. Fever, joint and muscle pain and skin flushing or rash are typical symptoms. Later on in the disease, signs of haemorrhage in the skin and eyes can be seen and the circulatory system goes into shock.
These fevers have many of the characteristics needed to make them a serious risk if used as a bioweapon, such as a high death rate in people who become infected, and they are highly infectious by aerosol spread. This means that a sufficient quantity of live virus could be aerosolised over an urban area by the detonation of a weapon and so result in a serious outbreak of disease.
Haemorrhagic fever viruses are reported to have been developed as weapons by several countries in the past, including the USA, although all such research and development should have been stopped by countries ratifying the Biological Weapons Convention.
Apart from yellow fever, the haemorrhagic fevers do not have licensed vaccines to prevent them.
Ricin
Ricin is a deadly poison made from the seeds of the castor bean. It is not a live organism, like a virus or bacterium, but a biological poison. It can be extracted fairly easily from the waste left over from processing castor beans. Only a very small amount is needed to kill.
The Bulgarian Georgi Markov was assassinated with ricin in London in 1978. On Waterloo Bridge on his way to work, he was bumped by a man carrying an umbrella. The umbrella injected into his leg a tiny metal ball, which after his death was found to contain traces of ricin.
People can be exposed to ricin by being injected with it, by swallowing it or by breathing it in. It stops the body from making proteins. Without proteins, the cells of the body start to die. If ricin is eaten or injected, the liver and kidneys would stop working and the person would eventually die from multi-organ failure. If ricin is breathed in, after various respiratory symptoms, such as coughing, the lungs might fail. It can be hours before any symptoms appear.
Ricin normally exists as a white powder and is a very stable compound. It can be mixed with water or other liquids to make an aerosol or a liquid mix (such as was found in a station locker in Paris in March 2003).
Last Reviewed: 30 April 2003
