Anthrax and biological warfare
Anthrax is a severe infectious disease caused by the bacterium Bacillus anthracis, commonly found in soil. It poses significant health risks to both humans and animals, making it a potential agent for biological warfare. The bacterium's ability to form resilient spores enables it to survive in harsh environments for long periods, enhancing its appeal for use in military applications. Anthrax infections can occur through inhalation, ingestion, or skin contact with contaminated materials, each presenting distinct symptoms and varying mortality rates. Effective detection methods and timely antibiotic treatment are crucial for managing anthrax cases, with vaccines available to prevent exposure.
Historically, anthrax has been explored as a biological weapon, with notable instances including British military experiments in World War II and the infamous 2001 anthrax attacks in the United States, which resulted in fatalities. These events underscore the importance of preparedness and response strategies, as outlined by health authorities like the CDC. Additionally, microbial forensics plays a vital role in identifying the strains of anthrax used in bioterrorism, aiding in the response to and prevention of future incidents. Understanding anthrax's characteristics and implications is essential for ensuring public safety and security in the face of biological threats.
Anthrax and biological warfare
DEFINITION: Deadly disease caused by the soil bacterium Bacillus anthracis.
SIGNIFICANCE: Because anthrax is capable of debilitating and killing people and animals quickly, it is an attractive agent for use in biological warfare. The abilities to detect, treat, and neutralize anthrax efficiently are thus necessary to ensure public safety.
The bacterium Bacillus anthracis resides in soil, and, like other members of the bacterial genus Bacillus, can make a highly resistant resting cell known as an endospore. Endospores can withstand heat, desiccation, harsh chemicals, and ultraviolet radiation and can last in soils for centuries. Anthrax, the disease caused by B. anthracis, afflicts herbivorous animals, but human anthrax infections result from contact with infected animals or animal products.
Types of Anthrax Infections
Anthrax is caused by the inhalation or ingestion of B. anthracis endospores or, in the case of cutaneous anthrax, by contact between damaged skin and B. anthracis. Inhalation of endospores causes inhalation anthrax, which typically occurs among workers in textile or tanning industries who handle contaminated animal products such as wool, hair, and hides. The incubation period of inhalation anthrax ranges from one to six days, and the disease follows a two-stage progression. After infection, the patient develops a dry cough, muscle weakness, tiredness, fever, and pressure in the middle of the chest. The second stage begins with the onset of respiratory distress and typically culminates in death within twenty-four hours. Inhalation anthrax has a mortality rate of 95 percent if untreated.
Gastrointestinal anthrax results from the ingestion of undercooked, contaminated meat. Two to seven days after ingestion, abdominal pain and fever occur, followed by vomiting, nausea, and diarrhea. Gastrointestinal bleeding is observed in some severe cases, and dissemination of the disease throughout the body also results. Fluid loss can result in shock and kidney failure. Approximately 50 percent of cases of gastrointestinal anthrax are lethal.
Cutaneous anthrax results from invasion of the skin by B. anthracis. If the skin is damaged by scrapes, cuts, or insect bites, endospores can breach the outer layers of the skin and infect it. After an incubation period of two to five days, small solid and conical elevations of the skin devoid of pus called papules form; these papules then swell, rupture, and blacken. Without treatment, anthrax skin infections can disseminate to other systems, and death occurs about 20 percent of the time.
Detection of Anthrax
Growing B. anthracis from a blood sample is the best way to demonstrate an anthrax infection in patients who have not yet been given antibiotics. In patients who have begun antibiotic therapy, serological methods that detect antibodies made by the immune system against the bacterium are efficacious. Blood samples from a person who has died from anthrax should yield copious quantities of relatively large, rod-shaped bacteria that are encapsulated and easily visualized with polychrome methylene blue stains.
Automated detection systems (ADSs) can determine whether B. anthracis endospores have been released into a setting. The BSM-2000 (Universal Detection Technology), for example, continuously samples the air and heats it. Captured, heated spores release dipicolinic acid (DPA), a compound unique to bacterial endospores. DPA binds to terbium ions (Tb3+), which, together, fluoresce green under ultraviolet light. Other ADSs use Polymerase chain reaction (PCR) to test the air for (deoxyribonucleic acid) sequences specific to B. anthracis.
Treatment and Prevention of Anthrax
Several antibiotics are effective in the treatment of anthrax infections. High-dose intravenous penicillin G, ciprofloxacin, and doxycycline are typically quite effective. Preventive treatments with oral ciprofloxacin or doxycycline for six weeks are also effective. Anyone exposed to anthrax should begin treatment immediately because the disease can become untreatable with the passage of time.
BioThrax (made by Bioport Corporation) is a vaccine against anthrax. It consists of an extract prepared from a non-disease-causing strain of B. anthracis. It is administered as three inoculations given under the skin at two-week intervals, followed by booster injections at six, twelve, and eighteen months, after which yearly boosters are necessary to maintain immunity. BioThrax vaccinations are 93 percent effective in preventing anthrax infections.
When bodies or clothes are contaminated with B. anthracis endospores, personal contact can spread the disease. Washing with antibacterial soap and water and treating the wastewater with bleach can rid contaminated bodies of all endospores. Burning contaminated clothing and the corpses of those who have died from anthrax is an effective means of liquidating anthrax from the environment. Burial does not kill endospores. Endospores of B. anthracis released into the air are easily removed by means of high-efficiency particulate air (HEPA) or P100 filters.
Decontamination of areas that have been exposed to B. anthracis presents several challenges because the bacterial endospores are rather difficult to destroy. Ethylene oxide, chlorine dioxide, liquid bleach, and a decontamination foam created by Sandia National Laboratories kill B. anthracis endospores slowly. A cleanup method approved by the Environmental Protection Agency (EPA) that utilizes liquid bleach, water, and vinegar requires contact with a surface for at least sixty minutes. If chlorine dioxide is used in combination with an iron-based catalyst, sodium carbonate, and bicarbonate, disinfection requires only thirty minutes.
Anthrax as a Biological Weapon
Many nations have examined the potential of B. anthracis as a biological weapon. Growing B. anthracis is extremely easy, but processing the endospores into a form that is easily disseminated is extremely difficult. The first attempts to use anthrax as a biological weapon utilized rather crude methods. During World War II, the British military experimented with anthrax on Gruinard Island. This experiment so thoroughly contaminated the site that it was quarantined for the next fifty years. Britain then manufactured some five million “N-bombs,” which were anthrax-laced explosive devices, to attack German livestock, but the bombs were never used. In 1986, the British government hired a private company to disinfect the soil of Gruinard Island. The company first carted away the island’s topsoil in sealed containers and then used 280 tons of formaldehyde mixed with 2,000 tons of seawater to disinfect the soil that remained. In 1990, the British defense minister declared the island safe.
At Fort Detrick in Frederick, Maryland, the US Army developed a special form of anthrax endospores for use as a biological weapon. Such weaponized endospores lack the ionic charges that ordinarily cause them to stick together. Consequently, the spores are easily dispersed as a fine powder that can float for miles on the wind. On November 25, 1969, an executive order from President Richard M. Nixon outlawed offensive biological weapons research in the United States. All existing US stockpiles of biological weapons were subsequently destroyed.
Despite the fact that it was a signatory to the international Biological Weapons Convention of 1972, which was intended to end the production of biological weapons, the Soviet Union produced extensive quantities of weapons-grade anthrax endospores. On April 2, 1979, more than one million people in Sverdlovsk (now Yekaterinburg), Russia, were exposed to an accidental release of anthrax organisms from the local biological weapons plant. More than sixty people died from inhalation anthrax. An extensive KGB-sponsored cover-up from 1979 to 1992 prevented the international community from learning the truth of what happened until Russian president Boris Yeltsin admitted Soviet involvement in this incident. In Africa, South African intelligence services helped the Rhodesian government of Ian Smith use anthrax against humans and the cattle of the black nationalists who were fighting against his government during the late 1970s.
Weaponized endospores were used in the United States during the final four months of 2001, when spores of B. anthracis were mailed within the continental United States. Eleven cases of inhalation anthrax and eleven cases of cutaneous anthrax resulted from these attacks, and five people died.
In 2024, the Center for Disease Control (CDC) recommended that communities develop an emergency prepardness plan in case of anthrax attack. This plan involved maintaining a written family medical history and knowing the symptoms of anthrax exposure. The CDC also recommended that in the event of an anthrax-based emergency, the community attempt to collectively secure antibiotics from the federal government at designated dispensing points.
Anthrax and Microbial Forensics
Microbial forensics is concerned with the isolation and identification of any microbes used during bioterrorist attacks. Upon arrival at the site of an attack, the microbial forensics team must remove all persons from the site and decontaminate them. Sample collections taken from the air, vents, countertops, sinks, floors, and other surfaces can help the scientists to determine the source of the infection. All samples collected must be properly identified and stored in tamper-proof containers to preserve the chain of custody.
By identifying the exact strain of B. anthracis involved in an anthrax outbreak, experts can determine whether the disease has occurred as the result of a bioterrorism attack or as a naturally acquired infection. Various strains of B. anthracis show very little DNA sequence variation, but because the entire genome of this organism has been completely sequenced, scientists are able to use PCR to detect single base differences between strains, called single nucleotide polymorphisms (SNPs), and thus provide a fingerprint for each B. anthracis strain. If the strains found at the scene of an attack and in the infected individuals are the same, then the agent used in the bioterrorism attack is confirmed. This information can be used in determining both the source of the biological weapon employed and the best treatment options. Molecular forensics identified the strain used in the 2001 postal attacks on American soil as the Ames strain of B. anthracis, which was, ironically, developed at Fort Detrick.
Bibliography
Alibek, Ken, with Stephen Handelman. Biohazard: The Chilling True Story of the Largest Covert Biological Weapons Program in the World—Told from Inside by the Man Who Ran It. London: Hutchinson, 1999. Print.
"Bioterrorism and Anthrax: The Threat." CDC, 10 May 2024, www.cdc.gov/anthrax/bioterrorism/index.html. Accessed 15 Aug. 2024.
Decker, Janet. Anthrax. New York: Chelsea, 2003. Print.
Guillemin, Jeanne. Anthrax: The Investigation of a Deadly Outbreak. Berkeley: U of California P, 2001. Print.
Holmes, Chris. Spores, Plague, and History: The Story of Anthrax. Dallas: Durban, 2003. Print.
Miller, Judith, Stephen Engelberg, and William Broad. Germs: Biological Weapons and America’s Secret War. New York: Simon, 2001. Print.
Nikolakakis, Ioannis, et al. "The History of Anthrax Weaponization in the Soviet Union." National Library of Medicine, 28 Mar. 2023, www.ncbi.nlm.nih.gov/pmc/articles/PMC10134958/. Accessed 14 Aug. 2024.
Wheelis, Mark, Lajos Rózsa, and Malcolm Dando, eds. Deadly Cultures: Biological Weapons Since 1945. Cambridge: Harvard UP, 2006. Print.