Potential Agents for Biological Attack   The agents that are most likely to be used in a biological event are categorized according to their potential for serious illness, and ease of transmission.  The agents in the three categories are listed below.  Click on the name of the agent to find more information.  A full list of potential bioterrorism disease agents and their descriptions is available at the Centers for Disease Control and Prevention (CDC) web site at http://www.bt.cdc.gov/ .  This site also contains information on chemical, radiological and other threats.   Category A: Anthrax (Bacillus anthracis)      Botulism (Clostridium botulinum toxin)       Plague (Yersinia pestis)       Smallpox (variola major)       Tularemia (Francisella tularensis)       Viral hemorrhagic fevers (filoviruses and arenaviruses) Category B:       Brucellosis (Brucella species)       Epsilon Toxin of Clostridium perfringens       Food safety threats (Salmonella species, Escherichia coli 0157:H7, Shigella)       Glanders (Burkholderia mallei)       Melioidosis (Burkholderia pseudomallei)       Psittacosis (Chlamydia psittaci)       Q fever (Coxiella burnetii)       Ricin toxin from Ricinus communis (castor beans)       Staphylococcal enterotoxin B       Typhus fever (Rickettsia prowazekii)       Viral encephalitis (alpha viruses e.g., Venezuelan equine encephalitis, Eastern * Western equine encephalitis)       Water safety threats e.g., Vibrio cholerae, Cryptosporidium parvum) Category C:       Nipah virus       Hantaviruses       Tick-borne hemorrhagic fever viruses       Tick-borne encephalitis viruses       Yellow fever       Multidrug-resistant tuberculosis