Biological weapons contain living bacterial or viral organisms, or the toxins produced by them. The toxins are generally the most lethal and act the quickest, producing incapacitation or death within minutes or hours. Bacterial and viral pathogens require an incubation period of 24 hours to six weeks before the appearance of symptoms.

Bacterial agents include anthrax, meloidosis, bubonic and pneumonic plague and glanders.

Viral agents include smallpox, yellow fever, equine encephalitis, influenza and ebola virus.

Toxins include botulinum toxin, ricin and various mycotoxins.

Biological weapons are hundreds to thousands of times more lethal than chemical weapons. A few pounds of biological agents can be as devastating as thousands of tons of chemical agents. However, most biological agents must be inhaled or ingested in order to be effective, which makes them easier to defend against than chemical agents. Most biological agents degrade rapidly, but many spore-forming bacteria, such as anthrax, are persistent. Anthrax spores can remain in the soil in deadly form for decades.

Under ideal weather conditions, a Scud warhead filled with botulinum could contaminate an area of 2,300 square miles. A similar warhead filled with the nerve agent sarin could contaminate 140 square miles.
According to the United Nations, Iraq may have retained as many as 16 ballistic missiles with biological-delivery capability. Iraq may also have a modified aircraft drop tank (which could be attached to a fighter plane or remotely piloted aircraft) designed to spray up to 500 gallons of biological agents.
This is not the only way of delivering a biological agent. In a terrorist attack it is much more likely the bacteria or virus will be spread from the ground and much more local.

The main potential targets of biological weapons include troop concentrations, logistics centres, command and control posts, air bases, ports, key infrastructure installations (such as oil and power facilities and desalination plants) and civilian population centres. Biological warfare would be particularly useful against large ships that can withstand multiple conventional hits, such as U.S. aircraft carriers.
However, in the wake of the recent terror attacks, it should be considered that civilian population centres at multiple points would most likely be the preferred targets by these groups.

FastCounter by bCentral
Since 2001-10-09.