The U.S. public health system and primary healthcare providers must be prepared to address various biological agents, including pathogens that are rarely seen in the United States. High-priority agents include organisms that pose a risk to national security because they

• can be easily disseminated or transmitted from person to person;
• result in high mortality rates and have the potential for major public health impact;
• might cause public panic and social disruption; and
• require special action for public health preparedness.

Second highest priority agents include those that

• are moderately easy to disseminate;
• result in moderate morbidity rates and low mortality rates; and
• require specific enhancements of CDC's diagnostic capacity and enhanced disease surveillance.

Third highest priority agents include emerging pathogens that could be engineered for mass dissemination in the future because of

• availability;
• ease of production and dissemination; and
• potential for high morbidity and mortality rates and major health impact.