Although the threat of a bioterrorist attack using Yersinia pestis, the germ that causes plague, is unlikely, there are examples throughout history of Y. pestis being used as a bioweapon. If such an emergency were to occur in the United States, CDC and other federal agencies would work closely with state and local partners to coordinate a response.
Why is plague a concern?
There is concern about plague and bioterrorism because without prompt treatment, the disease can cause serious illness or death. Y. pestis has been classified in the highest risk category of agents with potential to be used as a biological weapon. As a Tier 1 agent, Y. pestis, along with other select agents and toxinsexternal icon, presents the greatest risk of deliberate misuse and harm. This type of bacteria exists in nature in many parts of the world and could be grown in a laboratory in a form that could be released in the air. Even so, manufacturing an effective bioweapon using Y. pestis would require advanced knowledge and technology.
If the bacteria that cause plague were used in a bioterrorist attack, people exposed to the bacteria would be at risk of getting sick but could take antibiotics to prevent illness. There is no vaccine currently available in the United States to prevent plague. New plague vaccines are in development but are not expected to be commercially available in the immediate future.
What might a bioterrorist attack with plague look like?
An outbreak of plague following the use of Y. pestis as a bioweapon could be very different from a naturally occurring plague outbreak. Y. pestis would most likely be used in an aerosol attack, with tiny particles or droplets containing Y. pestis being released in the air (for example, dusts, mists, or fumes). People who inhale Y. pestis could then develop pneumonic plague (infection of the lungs). Pneumonic plague is the most serious form of the disease and the only form that can spread from person to person. As a result of a bioterrorist attack, sick people would likely be seen outside the areas where plague naturally occurs due to the potential for release in other areas and person-to-person spread between close contacts. The number of people infected in a bioterrorism outbreak would depend on many factors, including the area of distribution, quantity of Y. pestis distributed, and environmental conditions like wind and rain.