Appendix CHarmful Properties of Biological Agents
WARFARE AGENTS
Bacteria
Bacteria are microscopic, one-celled, plant-like organisms that range from 0.1 to 10 microns in diameter. They can be classified by shape as bacilli (rod), cocci (spherical), and spirilla (spiral). Bacteria are widely distributed in nature and can grow on artificial materials in the absence of other living cells.
Among the bacteria that are considered the most likely candidates for use as biological warfare agents are Bacillus anthracis (anthrax), Vibrio cholera (cholera), Yersinia pestis (plague), Franciscella tularensis (tularemia [rabbit fever or deer-fly fever]), and Brucellosis suis (brucellosis or undulant fever). Many other species are less dramatic but still pathogenic, such as Salmonella typhimurium (gastroenteritis, known as food poisoning), Staphylococcus aureus, and Shingellar dysenteriae (dysentery). Some agents usually affect animals but can be transmitted to humans with severe effects. Examples include Burkhoderia mallei (glanders) and Burkhoderia pseudomallei (melioidosis).
Rickettsia
Rickettsia are intracellular microscopic organisms intermediate between bacteria and viruses. They are oblong and vary in size from 0.3 to
0.5 microns in length and 0.3 micron in width. Like viruses, rickettsia cannot reproduce outside of a living organism. Rickettsia that are likely candidates for warfare agents are Coxiella burnetti, which causes Q fever and a chronic endocarditis; Rickettsia prowasecki, the causative agent of epidemic typhus; and Rickettsia ricketsii, the causative agent of Rocky Mountain spotted fever. Table C-1 provides a summary of the disease, likely transmission pathway, lethality, and infectivity associated with selected rickettsia agents.
Viruses
A virus is a microscopic organism consisting mainly of a nucleic acid in a protein coat. Viruses are shaped like rods or spheres and range in size from about 0.01 to 0.3 micron. Viruses cannot multiply on their own, but inside a living cell they become active organisms that can multiply. The viruses considered for potential use in warfare include the Ebola virus, Hanta virus, Venezuelan equine encephalitis virus, yellow fever virus, Rift Valley fever virus, the Junin virus (Argentine hemorrhagic fever), the variola virus (smallpox), and the Dengue fever virus. Table C-1 provides a summary of the disease, transmission, pathway, and lethality associated with selected viral agents. Infectivity is not currently available for most viruses. Many are transmitted by ticks and mosquitoes. Others are transferred by human contact.
Biological Toxins
Biological toxins are harmful chemical compounds produced by living organisms. Two toxins commonly associated with biological warfare are Botulinum and Clostridium perfringens. Botulinum, which is extremely potent, causes respiratory paralysis; the victim suffers from asphyxia. Clostridium perfiingens causes gas gangrene in which extremities "go necrotic" by slowly suffocating them. Table C-2 provides a summary of the sources, lethality, and required detection capability for selected toxins.
Genetically Altered Organisms
The last group of organisms that are used, or could be used, for warfare are genetically altered organisms. A group planning to develop a genetically altered organism would most likely aim for a more virulent or less treatable mutant of one of the agents described above. A toxin or substance created or acquired through recombinant technology would also be included in this category.
TABLE C-1 Exposure Factors for Selected Biological Warfare Agents
Agent |
Disease |
Transmission |
Lethality |
Infectivity |
Required Detection Capabilitya |
Bacteria |
|||||
Bacillus anthracis |
Anthrax |
Spores in aerosol |
High ~ 100% |
10,000 organisms |
5,000 org/m3 air |
Vibrio cholera |
Cholera |
Food and water |
|
|
|
|
|
Aerosol |
Low with treatment |
1 million organisms |
500,000 org/L water |
Yersinia pestis |
Pneumonic plague |
Aerosol inhalation |
High unless treated |
< 100 organisms |
50 org/m3 air |
Franciscella tularensis |
Tularemia (rabbit fever) |
Aerosol inhalation |
Moderate |
1 to 50 organisms |
< 25 org/m3 air |
Shigelladysenteriae |
Dysentery |
Inhalation and ingestion |
Moderate |
10 to 100 organisms |
25 org/m3 air 25 org/L water |
Rickettsia |
|||||
Coxiella burnetti |
Q fever |
Aerosol inhalation |
Very low |
10 organisms |
5 org/m3 air |
|
|
Food |
|
|
< 5 org/kg food |
Rickettsia rickettsii |
Rocky Mountain spotted fever |
Vectors |
Low |
N/A |
N/A |
Agent |
Disease |
Transmission |
Lethality |
Infectivity |
Required Detection Capabilitya |
Viruses |
|||||
Ebola virus |
Ebola |
Direct contact Aerosol |
High for Zaire strain |
N/A |
|
Venezuelan Equine Encephalitis (VEE) virus |
Encephalitis |
Vectors |
Low |
N/A |
|
Yellow fever virus |
Yellow fever |
Vector/tick |
Low |
N/A |
|
Rift Valley fever virus |
Rift Valley fever |
Vector/mosquito |
Low |
N/A |
|
Variola virus |
Smallpox |
Aerosol |
High to moderate |
N/A |
|
Hanta virus |
Hanta |
Aerosol |
43% in U.S |
N/A |
N/A |
Dengue fever |
Dengue fever |
Aedes mosquito |
Low to moderate |
N/A |
|
a These numbers were calculated by dividing the infectivity level by 2 m3 (the amount of air assumed to be breathed in two hours by an active adult) or by 2 L, the amount of water consumed during a day. Source: Boyle, 1998. |
TABLE C-2 Characteristics of Selected Biological Toxins
Source |
Toxin |
LD50(µG/kg) |
Required Detection Capabilitya |
Notes |
Bacteria |
||||
Clostridium botulinium |
Botulinium A, B, C, D, E |
~ 0.02 (inhalation) |
0.1 mg/m3 |
Among the most potent toxins known. |
|
|
1 (oral) |
0.02 mg/L (water or food) |
Delayed lethality. Persists in food and water. Breaks down within 12 hours in air. |
Clostridium perfringens |
Gangrene-causing enzyme |
0.1 to 5 |
0.3 mg/m3 |
Delayed action. Low mortality, but very debilitating. |
Clostridium tetani |
Tetanus toxin |
~ 3 |
N/A |
Delayed action. Relatively unstable and heat sensitive. |
Cornyebacterium diptheria |
Diptheria toxin |
0.03 |
N/A |
Lethal. Rapid acting. |
Staphylococcus aureus |
Staphylococcus enterotoxin A, B, C, D, E, (Toxicity is for for type B) |
0.4 (aerosol ED50) 20 (aerosol LD50) 0.3 (oral ED50) |
0.058 mg/m3 |
Rapid acting. Symptoms persist for us to 24-48 hours. Severely incapacitating. |
|
|
|
3 mg/m3 |
Can be lethal. Large-scale production feasible. |
|
|
|
0.007 mg/L |
Very stable. |
Dinoflagellates |
||||
Gonyaulax tamerensis, |
Saxitoxin |
1 (aerosol inhalation) |
0.01 mg/m3 (air) |
Lethal. |
Gonyaulax catanella, and related species |
(shellfish poison) |
7 (oral) |
0.2 mg/L |
Rapid acting. Soluble in water. Relatively persistent. |
Takifugu poecilonotuss |
Tetrodotoxin |
1.5 to 3 (inhalation) |
0.3 mg/m3 (air) |
Lethal. Rapid acting. |
|
|
30 (oral) |
0.7 mg/L |
Stable. |
Source |
Toxin |
LD50 (µG/kg) |
Required Detection Capabilitya |
Notes |
Algae |
||||
Anacystis species |
Anatoxin A |
170 to 250 (IP)b |
|
very fast death factor. |
Anabanea floss-aquae |
(VFDF) |
5,000 (oral) 2,100 (dermal) |
100 mg/L(kg) (water or food) |
Very rapid acting. |
Microcystis aeruginosa, |
Microcystin (FDF) |
25 to 100 (IP)b |
~10 mg/m3 (air) ~2 mg/L (water) |
Lethal, rapid acting Fast death factor. |
Microcystis, cyanea |
|
|
|
|
Fungi |
||||
Fusarium species |
Trichothecene mycotoxins |
25 to 500 (inhalation) |
40 mg/m3 (air) |
Nonlethal, delayed effects. Inhalation ingestion, dermal. |
("yellow rain") |
1,600 (oral) |
40 mg/L |
Very stable. Small repeated doses are cumulative. |
|
Plants |
||||
Ricinus communis |
Ricin |
1,000 |
150 mg/m3 (air) 20 mg/L (water) |
Lethal, delayed action. Easily produced. Persistent. |
Animals |
||||
Palythoa (soft corals) |
Palytoxin |
0.08 to 0.04 |
0.035 mg/m3 (air) 0.006 mg/L (water) |
Lethal and rapid acting. Stable. |
Conus geographus |
Contoxins |
3 to 6 |
~0.6 mg/m3 (air) ~0.1 mg/L (water) |
Water soluble. Highly stable |
Conus magnus fish-hunting cone snails) |
|
|
|
Can be used as aerosols. Easily synthesized. |
Phyllobates aurotaenia and |
Batrachotoxin |
0.1 to 0.2 |
0.015 mg/m3 (air) |
Rapid acting and lethal. very stable |
Phyllobates terribilis (Columbian frog) |
|
|
|
Can be synthesized. |
a Assumes 70-kg adult breathing at a rate of 0.016 m3/min for 30 minutes for air or the ingestion of 3 L water or 3 kg food by a 70-kg adult b IP refers to intraperitoneal injection dose to mice. Source: Boyle, 1998. |