An undercurrent of fear that terrorists may turn to biological weapons as their next mode of attack against the United States is slowly growing. Pneumonic Plague, a highly lethal and contagious form of the Plague, is one such agent.
Why? In the 1950s and 60s, more than 10 institutes and thousands of U.S. and Soviet scientists were reported to have worked on biological weapons programs, developing techniques to aerosolize Plague particles - leading directly to the contraction of Pneumonic Plague.(1) In the wrong hands, such techniques pose a potentially serious threat to any population which falls victim to such attacks.
However, Pneumonic Plague has not been reported in the U.S. since 1925.(2)
What is it?
The Plague presents in three forms: Pneumonic,
Bubonic and Septicemic. These infections are caused by the bacteria
Yersinia Pestis, historically present primarily in rats and fleas.
The first great Plague pandemic began in Egypt in 451AD. Over the next 4 years, the illness swept around the world; attributed population losses during that time were between 50-60%. In 1346, the second pandemic outbreak occurred (also known as "the Black Death"), and within 5 years had ravaged the Middle East, killed more than 13 million people in China, and 20-30 million more in Europe. The third pandemic began in 1855, spread to all inhabited continents, and ultimately killed more than 12 million people in India and China alone.(3)
How can it be contracted?
The Plague is normally transmitted from
an infected rodent to humans through infected fleas. Given advances
in public health, living conditions and medical therapies, future mass
outbreaks are highly improbable and unlikely.
In the case of a bioterrorism-related outbreak, the illness would likely be transmitted through the use of aerosol, causing a Pneumonic Plague pandemic. A 1970 World Health Organization assessment asserted that, in a worst case scenario, the dissemination of 50 kg of Yersinia Pestis in an aerosol cloud over a city of 5 million people would likely result in 150,000 cases of Pneumonic Plague; 80,000-100,000 of which would require hospitalization, and 36,000 of which would be likely expected to die.(4) Without treatment of any sort, fatality rates in cases of Pneumonic Plague are 100%.(5)
Bubonic and Septicemic Plague are not readily transmitted from human to human. Pneumonic Plague, however, is highly contagious and can be easily spread from one person to another through cough droplets.
What are the symptoms?
Symptoms can start as early as 2 days
after exposure(6) and include fever, cough with bloody, thick
and/or
watery sputum, and x-ray evidence of pneumonia. Laboratory tests
and cultures must be conducted in order to ensure a positive diagnosis.
Without early intervention and treatment, rapid evolution of the disease
can occur 2-4 days after symptom onset and can lead to septic shock with
high mortality.
How is it treated?
There is currently no vaccine available
against the Plague; however, current antibiotic therapies such as streptomycin,
tetracycline, gentamicin and chloramphenicol are all effective against
diagnosed cases. Such therapy should also be administered prophylactically
in cases of face to face exposure with an infected person.(7 &
8)
More Information:
There is no reason to assume that a bioterrorist
attack using Pneumonic Plague as a weapon is going to occur. To keep
informed of the latest updates and information on Plague and other biological
agents, please visit the Centers for Disease Control online at http://www.cdc.gov/,
the U.S. Department of State's website at http://www.state.gov/www/global/terrorism/,
and the Environmental Protection Agency's Counter-terrorism page at http://www.epa.gov/swercepp/cntr-ter.html.
References:
1, 3 & 4: Johns
Hopkins University Center for Civilian Biodefense Studies; http://www.hopkins-biodefense.org/pages/agents/agentplague.html
2 & 5: Neal R. Chamberlain,
Ph.D.; http://www.kcom.edu/faculty/chamberlain/Website/lectures/lecture/plague.htm
6: Bioterrorism Information
Sheets, San Francisco Bay Association for Professionals in Infection Control
and Epidemiology
7: Johns Hopkins University
on behalf of its Center for Civilian Biodefense Studies; http://www.hopkins-biodefense.org/pages/agents/agentplague.html
8: JAMA 2000;283:2281-2290
Copyright © 2001 by HCGuidone.