Biotoxins

DEFINITION: Toxic substances that originate from biological sources, including viruses, bacteria, fungi, algae, and plants.

SIGNIFICANCE: Biocrimes present law-enforcement agencies with serious challenges, as the perpetrators of such crimes can use numerous pathogens that exist naturally and do not require sophisticated expertise or technology to prepare. Further, because the effects of biotoxins are as diverse as the substances’ multiple origins, it can be difficult for investigators to ascertain the types of biotoxins employed in particular crimes or terrorist attacks.

The use of biological agents and their toxins in criminal acts and as weapons of war has a long history. In the Far East, opium was the poison used for and for several centuries. In the fourteenth century, Mongol warriors used plague-infected bodies as weapons of war, triggering an outbreak that killed thousands. During the French and Indian War (1754-1763), the British approved a plan to distribute to Native American tribes blankets contaminated with smallpox. These examples, however, pale in comparison with the chilling prospects of modern bioterrorism aided by a rapidly expanding knowledge of biological agents, biotoxins, and their potential to wreak havoc in complex, interdependent societies.

Common Microbial Agents

Various microbes can be the sources of biotoxins, including viruses, bacteria, and fungi. It is relatively easy to propagate bacteria and fungi with small samples, but the propagation of viruses for use in biocrimes requires certain training and access to specific technologies. Some of the common viruses that produce devastating effects include smallpox, Ebola, and Marburg. Smallpox, a highly contagious virus, is transmitted easily and carries a high mortality rate. By the 1970s, a worldwide vaccination program had eradicated smallpox. Three decades later, only two places in the world still officially maintained live cultures of the virus: a laboratory of the Centers for Disease Control and Prevention (CDC) in the United States and a lab in Russia. The Ebola and Marburg viruses are also extremely lethal; both cause hemorrhagic fever and profuse bleeding from bodily orifices. No cure or effective treatment for Marburg hemorrhagic fever has yet been found.

Bacterial biotoxins include anthrax, botulism, plague, and tularemia. Bacillus anthracis, the bacterium that causes anthrax, produces spores that are extremely resistant to the environment and are highly infectious when inhaled. Botulism is caused by a potent neurotoxin produced by the bacterium Clostridium botulinum. Once inhaled or ingested, the toxin causes respiratory failure and paralysis. Plague is also highly contagious; it causes a type of pneumonia and can be fatal if not treated early. Francisella tularensis causes tularemia, a generally nonlethal disease that is extremely incapacitating; symptoms include weight loss, fever, and headaches.

Many fungi produce remarkable amounts of toxic secondary metabolites, some of which are toxins. Fungal toxins are grouped into two categories: mycotoxins, which are produced by common molds, and mushroom toxins, which are formed in the fleshy fruiting bodies of sac or club fungi. Mycotoxins are major contributing factors to many cases of food poisoning. Some mycotoxins, such as aflatoxins, are believed to be among the most potent known carcinogens. Ingestion of even minute amounts of aflatoxins over long periods of time through contaminated food can cause liver cancer. In 1974, hundreds of people were poisoned by aflatoxin-contaminated corn in India; more than one hundred died. Several members of the mushroom genus Amanita contain amanitin, one of the deadliest poisons found in nature. The poison contained in false morels, monomethyl hydrazine (MMH), can cause diarrhea, vomiting, and severe headaches; ingestion of this poison occasionally results in death.

Marine and Plant Biotoxins

Many plants produce poisonous secondary metabolites that induce toxic effects when the plants or their extracts are consumed. Although sensitivity to plant toxins may vary among individuals, a good correlation generally exists between the amount of poison ingested and the severity of the clinical symptoms. Some highly toxic substances derived from plants include ricin (derived from castor beans), aconitine (from monkshood), strychnine (from the vomit nut), and huratoxin (from jimsonweed, also known as thorn apple). Ricin has been employed as a murder weapon in many cultures. In South America, native tribes have long used various plants to prepare curare, a common name for a deadly poison used on the tips of arrows or darts.

Harmful algal blooms represent a real threat to virtually all US coastal and fresh waters. Potential impacts range from devastating economic effects to public health risks to ecosystem alterations. The phenomena commonly known as “red tides” produce extremely potent biotoxins. When such toxins accumulate in marine food chains, they cause mass mortalities of birds, fish, and marine mammals and often lead to closures of commercial and recreational fisheries. When humans accidentally consume seafood contaminated with algal toxins, illness develops and even death occurs in extreme cases. Two classes of algal toxins have been well studied: the paralytic shellfish poisoning (PSP) toxins and domoic acid, both of which act on nerve systems.

Microbial Forensics

Criminal investigations involving biotoxins rely on forensic scientists who work in the cross-discipline known as microbial forensics. It can be challenging at times to distinguish symptoms and signs that may be caused by toxins from those that are just variants of normal health. Physicians and forensic scientists may not be able to recognize early symptoms associated with particular pathogens or biotoxins. Often, the identification of particular biotoxins requires the careful study of highly skilled professionals using sophisticated analytical instruments. Biosensors are increasingly used to detect and identify biotoxins. Furthermore, confirmation of the presence of biological agents or toxins in samples is generally not enough to guarantee of a without other supporting evidence.

Bibliography

Beasley, Val Richard, et al. “Diagnostic and Clinically Important Aspects of Cyanobacterial (Blue-Green Algae) Toxicoses.” Journal of Veterinary Diagnostic Investigation 1 (October, 1989): 359-365.

Breeze, Roger G., Bruce Budowle, and Steven E. Schutzer, eds. Microbial Forensics. Burlington, Mass.: Elsevier Academic Press, 2005.

Cooper, Marion R., Anthony W. Johnson, and Elizabeth A. Dauncey. Poisonous Plants and Fungi: An Illustrated Guide. 2d ed. London: TSO, 2003.

Garrett, Laurie. The Coming Plague: Newly Emerging Diseases in a World Out of Balance. New York: Farrar, Straus and Giroux, 1994.

Nelson, Lewis S., Richard D. Shih, and Michael J. Balick. Handbook of Poisonous and Injurious Plants. 2d ed. New York: Springer, 2007.

Tang, Xiaoqian, et al. "Current Trends in Biosensors for Biotoxins (Mycotoxins, Marine Toxins, and Bacterial Food Toxins): Principles, Application, and Perspective." TrAC Trends in Analytical Chemistry, vol. 165, 2023, doi.org/10.1016/j.trac.2023.117144. Accessed 14 Aug. 2024.