Biological Agents

Synopsis

The six microorganisms posing the greatest public health threat: Variola major (smallpox), Bacillus anthracis (anthrax), Yersinia pestis (plague), botulinum toxin (botulism), Francisella tularensis (tularemia), and filovirus/arenavirus (hemorrhagic fevers).

Microorganisms may be released silently and without immediate effects. The spread of disease cannot be controlled until there is awareness of the signs of infection and identification of the agent. 

If an organism is easily spread from person to person, as in the case of smallpox, the number of casualties could run into the tens of thousands. 

The probability that such an attack will take place in Canada has been deemed to be low by the Canadian government. 

The probability of such an attack in the United States is significantly higher.

Any such attack in North America would have calamatous consequences. For example, projections based on a CDC model using Canadian data predicts, that, under certain conditions, an anthrax attack on 100,000 Canadians would result in 50,000 anthrax cases, 32,875 deaths, 332,500 hospitalization days, and a cost of $ 6.5 billion.

Without preparation for bioterrorist activities at all levels of government, emergency services will be uncoordinated and inefficient, communication will be fragmented, and panic among the public will be very probable.

One of the more important aspects of the response to terrorist acts involving deadly microorganisms is the speed with which the response plan goes into effect. Delay results in greater numbers of infected people.

• Biological agents can be dispersed by an aerosol spray which must be inhaled. 
• These agents can also be used to contaminate food, water and other products. Attention to basic food hygiene when traveling abroad is very important.
• Some chemical agents may be volatile--evaporating rapidly to form clouds of agent. Others may be persistent.
• These agents may act directly on the skin, lungs, eyes, respiratory tract or be absorbed through your skin and lungs causing injury.
• Choking and nerve agents damage the soft tissue in these organs.
• When properly used, appropriate masks are effective protection to prevent the inhalation of either biological or chemical agents; however this assumes an adequate warning. Gas masks alone do not protect against agents that act through skin absorption. Protective equipment for personal use is available from commercial vendors in the industrial and occupational health industries.
• There is an incubation period after exposure to biological agents. 
• It is essential that a person seek appropriate care for illnesses acquired while traveling abroad to assure prompt diagnosis and treatment.

The range of  biological agents of war or bio-terrorism changes over time. Technology allows for some pathogens, which in their natural state pose only minimal dangers, to be genetically engineered into more threatening forms having fewer if any cure at all. Their availability in nature also changes and science continues to discover new pathogens. 

The United States Center for Disease Control compiled a widely adopted list of the most dangerous biological agents. They are segregated into three categories, depending on a variety of factors.

• Category A agents are given highest priority regarding the need for public health preparedness. They are agents that pose a threat to national security due to ease of dissemination and transmission from person to person, result in high mortality rates, have the potential for a major impact on public health, may cause public panic and social disruption, and require special action for public health preparedness. Category A includes anthrax, botulism, plague, smallpox, tularemia, and viral hemorrhagic fevers.
• Category B agents are considered second highest priority. They pose a risk to national security because they are moderately easy to disseminate and result in moderate mortality rates. Category B includes brucellosis, epsilon toxin of clostridium perfringens, food safety threats (salmonella, escherichia coli, shigella), glanders, melioidosis, psittacosis, Q- fever, ricin toxin, staphylococcal enterotoxin B, typhus fever, viral encephalitis, and water safety threats (vibrio cholerae, crytosporidium parvum).
• Category C agents are given third highest priority. They are a threat to national security due to their availability, ease of production and dissemination, potential for high mortality rates, and impact on public health. This category includes agents that are emerging pathogens that could be engineered for mass dissemination such as the nipah virus and hantavirus.

Bio-Terrorism Topic Covered in Current Publications:

• Current Threats

• Al Qaeda Warnings

Category A Agents