Biological Warfare: Detection & Protection

By Dr. Bader Faiyaz Zuberi
Asst. Prof. Medicine, Dow Medical College
Karachi, Pakistan

Biologicalweapons include any organism or toxin found in nature that can be used to incapacitate, kill, or otherwise impede an adversary. Biological weapons are characterized by low visibility, high potency, substantial accessibility, and relatively easy delivery.

The potential spectrum of bioterrorism ranges from hoaxes and use of nonmass casualty agents by individuals or small groups to
state-sponsored terrorism that employs classic biological warfare (BW) agents and can produce mass casualties. Such scenarios would present serious challenges for patient treatment and for prophylaxis of exposed persons. Environmental contamination could pose continuing threats.

The use of biological agents is not a new concept, and history is replete with examples of biological weapon use. Prior to the 20th
century, biological warfare took on 3 main forms:

(1) deliberate poisoning of food and water with infectious material,
(2) use of microorganisms or toxins in some form of weapon system, and
(3) use of biologically inoculated fabrics.

Attempts to use BW date back to antiquity. Scythian archers infected their arrows by dipping them in decomposing bodies or in blood mixed with manure as far back as 400 BC. Persian, Greek, and Roman literature from 300 BC quote examples of the use of animal cadavers to contaminate wells and other sources of water. In 190 BC, at the Battle of Eurymedon, Hannibal won a naval victory over King Eumenes II of Pergomon by firing earthen vessels full of venomous snakes into the enemy ships.

In the 12th century AD, during the battle of Tortona, Barbarossa used the bodies of dead soldiers to poison wells. In the 14th century AD during the siege of Kaffa, the attacking Tarter force hurled the corpses of those who died of plague into the city to attempt to inflict a plague epidemic upon the enemy. This was repeated in 1710 when the Russians besieging Swedish forces at Reval in Estonia catapulted plague cadavers.

In the 18th century AD during the French and Indian War, British forces in North America gave blankets from smallpox patients to the Native Americans to create a transmission of the disease to the immunologically naïve tribes. In 1863, a confederate surgeon was arrested and charged with attempting to import yellow fever-infected clothes into the northern parts of the US during the Civil War.

Biological warfare became more sophisticated against both animals and humans during the 1900s. During World War I, the Germans developed anthrax, glanders, cholera, and a wheat fungus for use as biological weapons. They allegedly spread plague in St Petersburg, infected mules with glanders in Mesopotamia, and attempted to do the same with the horses of the French Calvary.

In 1925, the Geneva Protocol was signed by 108 nations, including the 5 permanent members of the UN Security Council. This was the first multilateral agreement that extended prohibition of chemical agents to biological agents. No method for verification of compliance was addressed.

During World War II, the Japanese operated a secret BW research facility in Manchuria and carried out human experiments on Chinese prisoners. They exposed more than 3000 victims to plague, anthrax, syphilis, and other agents. Victims were observed for development of disease, and autopsies were performed.

In 1942, the US formed the War Research Service. Anthrax and botulinum toxin initially were investigated for use as weapons, and sufficient quantities of botulinum toxin and anthrax cattle cakes were stockpiled by June 1944 to allow limited retaliation if the Germans first used biological agents. The British tested anthrax bombs on Gruinard Island off the northwest coast of Scotland in 1942 and 1943 and then prepared and stockpiled anthrax-laced cattle cakes.

The US continued research on various offensive biological weapons during the 1950s and 1960s. >From 1951-1954, simulants (Bacillus globigii, Serratia marcescens) were released off both coasts of the US to demonstrate the vulnerability of American cities to biological agent attacks. This vulnerability was tested again in 1966 when the simulant B globigii was released in the New York subway system.

In 1957, the British government decided to end its offensive BW capabilities and destroy its weapon stockpiles.

The US terminated its offensive biological weapons program in 1969 for microorganisms and in 1970 for toxins. The US is a signatory nation of the Biological Toxin Weapons Convention of 1972. This convention addressed the prohibition of the development, production, stockpiling, and destruction of bacteriologic and toxin weapons. Signatories to this agreement are required to submit information annually to the United Nations concerning facilities where biological defense research is being conducted, scientific conferences that are held at specified facilities, exchanges of scientists or information, and disease outbreaks. American stockpiles of biological weapons were destroyed completely by 1973.

During the Vietnam War, Vietcong guerrillas used punji stakes dipped in feces to increase the morbidity from wounding by these stakes.

The Soviet Union (USSR) continued to develop biological weapons from 1950-1980. In the 1970s, the USSR and its allies were suspected of having used "yellow rain" (trichothecene mycotoxins) during campaigns in Loas, Cambodia, and Afghanistan. In 1979, an accidental release of anthrax from a weapons facility in Sverdlovsk, USSR, killed at least 66 people. The Russians denied this accident until 1992.

Since the 1980s, terrorist organizations have become users of biological agents. The most frequent bioterrorism episodes have involved
contamination of food and water. In September and October of 1984, 751 persons were infected with Salmonella typhimurium after an intentional contamination of restaurant salad bars in Oregon by followers of the Bhagwan Shree Rajneesh.

In 1985, Iraq began an offensive biological weapons program producing anthrax, botulinum toxin, and aflatoxin. During Operation Desert Shield, the coalition of allied forces faced the threat of chemical and biological agents. Following the Persian Gulf War, Iraq disclosed that it had bombs, Scud missiles, 122-mm rockets, and artillery shells armed with botulinum toxin, anthrax, and aflatoxin. They also had spray tanks fitted to aircraft that could distribute 2000 L over a target.

Currently, 17 countries are suspected of having an offensive BW program. In 1992, 20 people were administered chemoprophylaxis after a Virginia man sprayed his roommates with a substance that he claimed was anthrax. In 1994, a Japanese sect of the Aum Shinrikyo cult attempted an aerosolized release of anthrax from the tops of buildings in Tokyo. In 1995, 2 members of a Minnesota militia group were convicted of possession of ricin, which they had produced themselves for use in retaliation against local government officials. In 1996, an Ohio man was able to obtain bubonic plague cultures through the mail.

In 1997, the Defense Against Weapons of Mass Destruction Act directed the Department of Defense to establish a domestic preparedness program to improve the ability of local, state, and federal agencies to respond to biological incidents. During 1998 and 1999, multiple hoaxes occurred involving the threatened release of anthrax in the US that resulted in decontamination and antibiotic prophylaxis for the intended victims. Nearly 6000 persons across the US have been affected by these threats. To date, none of these cases involved actual anthrax bacteria. According to a study by the Centers for Disease Control and Prevention (CDC), an intentional release of anthrax by a bioterrorist in a major US city would result in an economic impact of $477.8 million to $26.2 billion per 100,000 persons exposed.

The threat that biological agents will be used on both military forces and civilian populations is now more likely than at any point in all of
history.

DELIVERY, DISSEMINATION, AND DETECTION OF BIOLOGICAL WARFARE AGENTS

Biological agents are easy to acquire, synthesize, and use. The small amount of agents necessary to kill hundreds of thousands of people in a metropolitan area make the concealment, transportation, and dissemination of biological agents relatively easy. In addition, BW agents are difficult to detect or protect against; they are invisible, odorless, tasteless, and their dispersal can be performed silently.

Dissemination of BW agents may occur by aerosol sprays, explosives (artillery, missiles, detonated bombs), or food or water contamination. Variables that can alter the effectiveness of a delivery system include particle size of the agent, stability of the agent under desiccating conditions, UV light, wind speed, wind direction, and atmospheric stability.

The use of an explosive device to deliver and disseminate biological agents is not very effective, since such agents tend to be inactivated by the blast. Contamination of municipal water supplies requires an unrealistically large amount of agent and introduction into the water after it passes through a regional treatment facility.

To be an effective biological weapon, airborne pathogens must be dispersed as fine particles less than 5 mm in size. Infection with an
aerosolized agent usually requires deep inspiration of an infectious dose. Advanced weapons systems (eg, warheads, missiles) are not required for the aerosolized delivery of biological agents. Low-technology aerosolization methods including agricultural crop-dusters; aerosol generators on small boats, trucks, or cars; backpack sprayers; and even purse-size perfume atomizers suffice. Aerosolized dispersal of biological agents is the mode most likely to be used by terrorists and military groups.

Detection of biological agents involves either finding the agent in the environment or medical diagnosis of the agent's effect on human or
animal victims. Early detection of a biological agent in the environment allows for early specific treatment and time during which prophylaxis would be effective. Unfortunately, currently no reliable detection systems exist for BW agents. The US Department of Defense has placed a high priority on research and development of a detector system. Methods are being developed and tested to detect a biological aerosol cloud using an airborne pulsed laser system to scan the lower altitudes upwind from a possible target area. A detection system mounted on a vehicle also is being developed. This system will analyze air samples to provide a plot of particle sizes, detect and classify bacterial cells, and measure DNA content, ATP content, and identify agents using immunoassays.

A BW agent attack is likely to be covert. Thus, detection of such an attack requires recognition of the clinical syndromes associated with various BW agents. Physicians must be able to identify early victims and recognize patterns of disease. This requires integrated epidemiologic surveillance systems performing real-time monitoring with information shared at many levels of the health care system (eg, ED to ED or ED to public health officials). Preliminary criteria for suspicious outbreaks of disease that could provide indications of a possible biological weapons event include the following:

• Disease (or strain) not endemic
• Unusual antibiotic resistance patterns
• Atypical clinical presentation
• Case distribution geographically and/or temporally inconsistent (eg, compressed time course)
• Other inconstant elements (eg, number of cases, mortality and morbidity rates, deviations from disease occurrence baseline)

Indications of possible BW agent attack include the following:

• Disease entity that is unusual or that does not occur naturally in a given geographical area or combinations of unusual disease entities in the same patient population
• Multiple disease entities in the same patients, indicating that mixed agents have been used in the attack
• Large numbers of both military and civilian casualties when such populations inhabit the same area
• Data suggesting a massive point-source outbreak
• Apparent aerosol route of infection
• High morbidity and mortality relative to the number of personnel at risk
• Illness limited to fairly localized or circumscribed geographic areas
• Low attack rates in personnel who work in areas with filtered air supplies or closed ventilation systems
• Sentinel dead animals of multiple species
• Absence of a competent natural vector in the area of outbreak (for a biological agent that is vector-borne in nature)

PROTECTIVE MEASURES

Protective measures can be taken against BW agents. These should be implemented early (if warning is received) or later (once suspicion of BW agent use is made). Currently, available masks such as the military gas mask or high-efficiency particulate air (HEPA) filter masks used for tuberculosis (TB) exposure filter out most BW particles delivered by aerosol. Multilayered HEPA masks can filter 99.9% of 1-5 mm particles, but face-seal leaks may reduce the efficacy by as much as 10-20%. Individual face-fit testing is required to correct seal leak problems.

Most aerosolized biological agents do not penetrate unbroken skin, and few organisms adhere to skin or clothing. After an aerosol attack, simple removal of clothing eliminates a great majority of surface contamination. Thorough showering with soap and water removes 99.99% of the few organisms left on the victim's skin after disrobing. The use of sodium hypochlorite is not recommended over soap and water.

The use of special suits by health care providers is not necessary. Normal clothing provides a reasonable degree of protection against
dermal exposure. Latex gloves and universal precautions provide sufficient protection when treating most infected patients. Place
patients in a private negative-pressure room and practice proper sanitation with universal precautions. Proper disposal of corpses is
essential. In the case of anthrax spores, this should be performed by incineration.

Of the potential BW agents, only plague, smallpox, and viral hemorrhagic fevers are spread readily person to person by aerosol and require more than standard infection control precautions (gown, mask with eye shield, gloves). Regardless, place all potential victims of BW agents in isolation. Medical personnel caring for these patients should wear a HEPA mask in addition to standard precautions pending the results of a more complete evaluation.

Broad-spectrum intravenous antibiotic coverage is recommended initially for victims when a BW agent is suspected. Institute this even prior to the identification of the specific BW agent. Vaccinations currently are available for anthrax, botulinum toxin, tularemia, plague, Q fever, and smallpox. The widespread immunization of nonmilitary personnel has not been recommended by any governmental agency. Immune protection against ricin and staphylococcal toxins may be feasible in the near future.

Date/Time Last Modified: 6/18/2002 8:07:46 AM

© 2004, Human Development Foundation. All rights reserved.
1350 Remington Road, Suite W, Schaumburg, Il. 60173
Toll Free: (800) 705-1310 | Email: info@yespakistan.com | Privacy Policy