Discuss the differences in clinical presentation between a person who is a victim of a chemical vs. a biological event. Biological agents are microorganisms (i.e. viruses, bacteria and fungi), whether naturally occurring, genetically modified or synthetically engineered. These agents may cause infection, toxicity or allergy in humans, animals or plants. Toxins are also classified as biological agents. These are naturally occurring poisonous chemicals produced by biological organisms, including plants, animals and microorganisms (although some may be artificially synthesized). As poisons, toxins are comparable to toxic chemical agents in their mechanism of action. Typical biological agents cause sickness and disease by infection, usually producing symptoms a number of days later. In general, these agents have long latency periods. The route of exposure to a biological agent can have a significant effect on the type and severity of infection. In addition, the method of transmission can have a significant impact on the spread of infection among a population. Some infections may be transmitted only by direct physical contact between individuals or contact with contaminated materials or surfaces. Others are spread from person to person by airborne transmission, enabling the potentially rapid spread of the disease. Some agents may require an insect vector to transmit the infection, e.g. the yellow fever virus carried by mosquitos. Chemical agents are toxic chemical substances that occur naturally or are artificially synthesized. Many are produced and used for legitimate industrial, agricultural or medical purposes, e.g. hydrogen cyanide (industrial), chlorine (industrial), organophosphates (agricultural) and carbamates (medical). Chemical agents developed under military chemical weapons programs include: • blister agents, such as Sulphur mustard (i.e. ‘mustard gas’), which cause burns and blisters on the skin upon contact and if inhaled damage the respiratory tract • nerve agents, such as sarin and VX, which interfere with the transmission of the acetylcholine neurotransmitter causing muscle spasms, secretions, respiratory failure and unconsciousness • blood agents such as cyanide, which inhibit transfer of oxygen in the blood causing convulsion and respiratory failure • choking agents, such as phosgene, which cause damage to the lungs resulting in respiratory problems • incapacitating agents, which act on the central nervous
system to cause psychomimetic effects (delusions and hallucinations), such as BZ, or to cause unconsciousness and respiratory failure, such as fentanyl
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- Spring '14
- Incident Command System, Chemical warfare, Biological warfare, Unified Command