The dissemination route (how an agent is spread) depends on many characteristics:
- How much of the agent is needed to cause illness / death?
- What is the best way to infect a person (inhale from the air, eat contaminated food,
absorb through the skin, etc.)?
- How long does an agent stay active in certain environments (air, food, water)?
- Some agents, such as anthrax, may have several ways of infection that make it a
more flexible agent of choice. Other agents may only infect people through one route
Particulate dissemination is usually introduced to the body through inhalation (breathing
into the lungs) of small particles that are in the air (aerosolized), and absorption
through the skin. This is the method of greatest concern for most public health
professionals since it offers terrorists the greatest ability to reach a large number
of people in any one attack. Particulate dissemination can be done using either
dry or wet forms of an agent, such as a fine powder or mist.
Food or Water Dissemination
Another route of concern, but historically shown to be less effective in harming
large numbers of victims, is by eating or drinking contaminated food or water. Water
contamination is not a likely target for terrorists because of the large amount
of agent needed and the regular treatment of each state’s water supply. If not enough
agent is used to contaminate water, the water itself will weaken the agent. In addition,
chlorine or other disinfectants are typically used to kill bacteria and other germs
in order to make drinking water safe. Food is also not considered the best way to
spread an agent because heating or cooking food can destroy most agents.
Though much less likely, exposure to vectors such as infected mosquitoes or other
insects may transmit disease to humans and animals.