A second issue is the dissemination of factual information concerning the real dangers of such an attack. Some (including members of this committee) would argue that the less is said, the better. However, American society does not respond without facts and public opinion programs. This means the actual dangers must be explained to the public and responsible political leaders without inflammatory rhetoric or disclosure of detailed methods for the assaults. In reaching a balance, we take some chance that plain speaking could motivate some to undertake the very actions we are trying to prevent. However candid discussion of the facts may help the public, the media, and health authorities respond in a calmer and more rational fashion than was observed with the aerosol anthrax attacks of 2001. The reality of those attacks is far more provocative than any abstract discussion (see Box 3-19).

Microbes could be delivered to a target population by multiple routes. Directly inoculating victims, infecting natural vectors or reservoirs and loosing them on the target population, or infecting a few people and counting on their spreading the infection even further are some possibilities. If we focus on terrorist strategies that can inflict mass casualties, however, none of these mechanisms is highly feasible today with the exception of smallpox, a virus that is well known to spread from human to human after a long and successful career in that evolutionary niche. If we conclude that other organisms must be delivered directly to the target host, we should also consider water, food, and aerosols as potential vehicles of infection. Contaminated water from wells and storage containers has been associated with outbreaks of disease, but the use of this approach for causing mass casualties is limited because of the dilution factor, chlorination, and the usual treatment of water before consumption in this country. Foodborne pathogens have caused many outbreaks in the United States and are a major cause of morbidity and mortality. Food items, however, are usually not consumed synchronously except at special events; although the extensive network of global commerce can assist in distributing an initial source over wide geographic areas. Improved surveillance of foodborne diseases and newer methods of molecular typing of offending organisms should provide a countermeasure to the possible wide dissemination of contaminated food. If a few cases are recognized and traced to a food source, warnings and recalls may serve to protect others from catastrophic harm.

The overall societal impact of any one of these dissemination methods could be considerable, regardless of the actual health damage. Case studies already exist, including nonlethal Salmonella infection of several hundred citizens (Torok et al., 1997); Sarin gas attacks with 12 deaths (Smithson, 2000); food tampering; and, most recently, anthrax delivered by letter and even anthrax hoaxes. Perhaps the most important route of attack, however, is aerosolization because of its ability to cause such large numbers of casu-



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