Bioterrorism involves the deliberate release of biological agents like bacteria, viruses, or toxins to cause disease or death in humans, animals, or plants. Such acts pose serious threats to public health and national security, highlighting the importance of public awareness and preparedness.
Categorizing Biological Threats
Biological agents are classified based on their potential to cause illness, ease of dissemination, and public health impact. The Centers for Disease Control and Prevention (CDC) classifies these agents into three categories (A, B, and C) to prioritize preparedness and response.
Category A agents are the highest priority due to their potential to pose a severe risk to national security. These agents are easily transmitted, result in high mortality rates, and have a significant public health impact. Examples include anthrax, smallpox, plague, botulism, tularemia, and viral hemorrhagic fevers.
Category B agents are the second highest priority, characterized by moderate ease of dissemination and lower mortality rates compared to Category A. They can cause moderate illness and require enhanced public health diagnostic capacity and disease surveillance. This category includes agents such as Brucellosis, Q fever, and certain food and water safety threats like Salmonella species.
Category C agents represent emerging pathogens that could be engineered for mass dissemination in the future. These agents are the third priority and include diseases like Nipah virus and Hantavirus. Preparedness for Category C agents focuses on ongoing research to improve detection, diagnosis, treatment, and prevention methods.
Examples of Key Bioterrorism Agents
Anthrax, caused by the bacterium Bacillus anthracis, is a bioterrorism concern because its spores can be easily produced in a dry form and spread through the air or as a powder. Infection can occur through inhalation, skin contact, or gastrointestinal exposure. Inhalation anthrax often presents with flu-like symptoms initially, progressing to severe respiratory issues, and can be fatal if not treated promptly.
Smallpox, caused by the Variola virus, was globally eradicated in 1980 through widespread vaccination efforts. Despite its eradication, it remains a concern due to its high person-to-person transmissibility and a fatality rate of approximately 30%. There is no specific treatment for smallpox, and prevention relies on vaccination, as routine vaccination is no longer widespread.
Botulism is a severe paralytic illness caused by the potent neurotoxin produced by Clostridium botulinum bacteria. This toxin can be absorbed through the respiratory or gastrointestinal tracts, leading to symptoms like double vision, blurred vision, difficulty swallowing, and progressive muscle paralysis, including respiratory muscles. The toxin’s extreme potency and ease of production make it a potential bioterrorism agent, especially if introduced into the food supply or aerosolized.
Plague, caused by the bacterium Yersinia pestis, manifests in three main forms: bubonic, pneumonic, and septicemic. Pneumonic plague, which infects the lungs, is concerning as a bioterrorism agent because it can spread from person to person through airborne droplets from coughing. This form develops rapidly and carries a high fatality rate, even with antibiotic treatment.
Tularemia, also known as “rabbit fever,” is caused by Francisella tularensis, a highly infectious bacterium. It can be acquired through various routes, including inhalation, contact with infected animals, or contaminated food and water. Symptoms commonly include fever, chills, muscle aches, and progressive weakness.
Viral Hemorrhagic Fevers (VHFs), such as Ebola, Marburg, and Lassa, are a group of illnesses caused by distinct virus families. These diseases are characterized by severe damage to the body’s vascular system, leading to symptoms like fever, malaise, and often internal or external bleeding. VHFs have high mortality rates, and some can spread from person to person through direct contact with infected bodily fluids.
Past Incidents of Bioterrorism
The 1984 Rajneeshee bioterror attack in The Dalles, Oregon, represents the largest confirmed bioterrorism incident in U.S. history. Members of a cult intentionally contaminated salad bars in ten local restaurants with Salmonella enterica Typhimurium bacteria. Their aim was to sicken the voting population and influence local elections, resulting in 751 documented cases of salmonellosis, with 45 individuals requiring hospitalization.
The 2001 Anthrax Attacks, also known as Amerithrax, involved the mailing of letters containing Bacillus anthracis spores to news media offices and U.S. senators beginning in September 2001. This act of bioterrorism led to five deaths and sickened 17 others. The investigation, code-named “Amerithrax” by the FBI, eventually traced the anthrax to a specific spore-batch maintained by a government scientist.
The Sverdlovsk anthrax leak in 1979 was an accidental release of Bacillus anthracis spores from a Soviet military facility in Sverdlovsk (now Ekaterinburg), Russia. A failure to replace an air filter led to the airborne dispersal of anthrax spores, resulting in an outbreak that killed at least 68 people. The exact number of victims remains unknown due to initial Soviet cover-ups.
During World War II, the Japanese Imperial Army’s Unit 731 conducted extensive biological warfare research and development in occupied Manchuria. This covert unit engaged in lethal human experimentation, infecting prisoners with various pathogens, including plague, cholera, anthrax, and smallpox, to study their effects and develop biological weapons. Estimates suggest their activities may have led to hundreds of thousands of deaths.
The Japanese cult Aum Shinrikyo made unsuccessful attempts to use biological agents, including botulinum toxin and Bacillus anthracis, in the early 1990s. Their biological weapons program largely failed due to technical difficulties in acquiring virulent strains and effectively disseminating the agents for mass casualties.