Bioterrorism and Public Health

Category “A” Biological Agents

Written by MicroDok

Category “A” Biological Agents are high-priority agents which pose the greatest security and health threat in a population. They are the primary most dangerous biological agents with the highest research preference due to their ease of dissemination, high morbidity, and high mortality. Agents in this category have the potential to cause mass public fear and societal disorder. Category “A” biological agents requires special public health preparedness and action, and they can be easily transmitted from person-to-person after being discharged in a defined animal or human population. They have the utmost potential for adverse security and public health impact which may result in multitudes of fatalities. Samples suspected to contain biological agents in Category “A” are analyzed in Biological Safety Level-4 (BL4) laboratories. BL4 laboratories are designed to handle and contain infectious specimens and pathogens that are suspected to be potentially dangerous to the general public.

Examples of biological agents in Category “A” include:

  • Bacillus anthracis – that cause anthrax.
  • Variola major (Smallpox) virus – that cause smallpox.
  • Yersinia pestis – that cause plague.
  • Francisella tularensis – that cause tularemia.
  • Haemorrhagic fever viruses (e.g. Ebola virus, Marburg, Lassa fever, Machupo, and Hantaviruses) – that cause viral haemorrhagic fevers.
  • Clostridium botulinum – that cause botulism.


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