Plague
There are three forms of plague, an infectious disease affecting animals and humans that is caused by the bacterium Yersinia pestis. Pneumonic plague occurs when Y. pestis infects the lungs; bubonic plague, the most common form of plague, is contracted by being bitten by an infected flea; septicemic plague occurs when the plague bacteria multiply in blood and can be a complication of pneumonic or bubonic plague, or can occur by itself.

Y. pestis used by terrorists in an aerosol attack could cause cases of the pneumonic form of plague. Pneumonic plague can be spread from person to person through direct and close contact. Others forms of plague cannot be spread from one person to another.

The first symptoms of pneumonic plague are fever, headache, weakness and rapidly developing pneumonia with shortness of breath, chest pain, cough and sometimes bloody or watery sputum. The pneumonia progresses for two to four days and may cause respiratory failure and shock. Without early treatment, patients may die.

Antibiotics given within 24 hours of the first symptoms will reduce the chance of death. In addition, antibiotic treatment for seven days will protect people who have had close contact with infected patients.

A plague vaccine is not currently available for use in the United States.