Chemical agents are inanimate, while bacteria, viruses, and other live agents may be contagious and reproductive. If they become established in the environment, they may multiply. Unlike any other weapon, they can become more dangerous over time. Certain biological agents incapacitate, whereas others kill, such as the Ebola virus. For Ebola, there is no cure or treatment. Interest in acquiring killer organisms for sinister purposes has grown among terrorists. Fortunately, biological terrorism has been limited to very few cases thus far. The capabilities of producing biological weapons in Iran, Iraq, Libya, Syria and North Korea are especially worrisome considering their histories of militant behavior. The failure to eliminate biological as well as chemical weapons may increase the likelihood of the development of a manmade plague. In this scenario, a large population cannot be protected against an attack. Vaccines can prevent some diseases, but unless the causative agent is known in advance, such a safeguard may be worthless. Most biological agents have no effect on or through intact skin, so respiratory masks and clothing would provide adequate protection for most people. Another challenge to biological defense is identifying an organism quickly. The Biological Integrated Detection System (BIDS) exposes suspected air samples to antibodies that react with a particular biological agent. A reaction of the antibody would signify the agent is present, a process that takes about 30 minutes. BIDS can now identify four agents: Bacillus anthracis (anthrax bacterium), Y. pestis (bubonic plague), botulinum toxin (the poison released by botulism organisms), and staphylococcus enterotoxin B (released by certain staph bacteria). The most effective safeguard against biological warfare and biological terrorism is prevention. The ProMED (Program to Monitor Emerging Diseases) surveillance system would include developing baseline data on endemic diseases throughout the world, rapid reporting of unusual outbreaks, and responses aimed at containing disease, such as providing advice on trade and travel. Steps to strengthen the 1972 Biological Weapons Convention through verification arrangements should be encouraged.