There are at least 11 different enterotoxin serotypes, produced by various biotypes of Staphylococcus aureus. All subtypes are structurally similar and produce the same clinical syndrome [94] . Enterotoxin B is a potent T-cell activator, and the clinical symptoms are largely mediated by the immune system rather than direct toxic effects. The toxin is heat-stable and relatively stable in aerosols. It is the second most common cause of food poisoning, and when inhaled, even low doses can produce symptoms. Although the fatality rate is only approximately 5%, a high percentage of those exposed could become seriously ill within a few hours [95] . In naturally occurring disease, approximately 15% become ill enough to require hospitalization. Contamination of food or water supplies with enterotoxin could debilitate a population or army within hours [1] .