Bioterrorism: Terrorism using biologic agents that are harmful to humans. Biological diseases and the agents that might be used for terrorism have been listed by the US Centers for Disease Control and Prevention (CDC). These agents include viruses, bacteria, rickettsiae (microorganisms that have traits common to both bacterial and viruses), fungi, and biological toxins. The biologica disease agents are classified into three categories, according to the degree of danger each agent is felt to pose. Category A poses high risk to national security because they can be easily disseminated or transmitted from person to person; cause high mortality, with the potential for major public health impact; might cause public panic and social disruption; and require special action for public health preparedness. Examples of Category A diseases include anthrax, botulism, the plague, smallpox, tularemia, and hemorrhagic fever due to the Ebola and Marburg viruses. Category B agents are moderately easy to disseminate; cause moderate morbidity and low mortality; and require specific enhancements of the CDC's diagnostic capacity and enhanced disease surveillance. Examples of Category B diseases include Q fever, Brucellosis, Glanders, Ricin toxin, epsilon toxin of the gas gangrene bacillus, and Staphylococcus enterotoxin B. Category C agents are emerging pathogens that could be engineered for mass dissemination in the future because of their availability; ease of production and dissemination; and potential for high morbidity and mortality and major health impact. Examples of Category C diseases include Nipah virus, Hantavirus, tickborne hemorrhagic fever and encephalitis viruses, Yellow fever, and Tuberculosis (multi-drug-resistant TB).