NOVA Online | Bioterror

The Black Death of the 14^th century was only one of three great plague pandemics that killed tens of millions of people.

Agents of Bioterror
Plague

incubation period | symptoms | how it would spread | treatment | vaccine

There are various forms of plague, all caused by the bacteria Yersinia pestis. Bubonic plague, historically the most common, is transmitted from rats to humans by infected fleas. In 1346, a bubonic plague pandemic known as the Black Death erupted in Europe and eventually killed 20-30 million people, a third of the population.

During World War II, the Japanese army reportedly dropped plague-infested fleas over China. It is possible that infected insects again could be used as weapons. But experts see a much greater risk in the spraying of Y. pestis in aerosols; inhaled bacteria would trigger cases of highly lethal pneumonic plague.

Experts consider plague a bioweapons threat for several reasons: The virus has been widely available in microbe banks for military and civilian researchers. Techniques to mass-produce and aerosolize plague were developed in the Soviet Union, and hundreds of former Soviet scientists may have this know-how. Finally, even a small number of plague cases are likely to sow panic given the infamous history of the disease.

Incubation period before symptoms
1-6 days

Symptoms

fever, chills, headache, weakness
nausea, vomiting, and abdominal pain
extreme lymph node pain (bubonic)
chest pain, cough, bloody or watery sputum (pneumonic)
septic shock

How it would be spread
Aerosol or person-to-person. Pneumonic plague is contagious through respiratory droplets.

Treatment
A variety of antibiotics can treat the disease but must be given soon after symptoms appear. Antibiotics given immediately after exposure may prevent disease onset.

Vaccine
No vaccine is available to the general public. A vaccine to prevent bubonic plague was licensed in the U.S. but discontinued by its manufacturers in 1999. Even if this vaccine becomes available, it does not prevent the pneumonic form of plague.

Anthrax	Botulism	Cholera	Glanders

Plague	Q Fever	Smallpox	Tularemia

Chart of the 8 agents

Photo: Corbis Images

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