Yersinia pestis, Biological Warfare, and Bioterrorism

June 14, 2017
Raymond A. Zilinskas

Excerpted from CBW Magazine

I teach a graduate seminar course at the Middlebury Institute of International Studies at Monterey titled “Chemical and Biological Weapons and Arms Control.” Last semester a student asked me, “Since the Japanese and Soviet biological warfare programs weaponized Yersinia pestis, is it possible that a terrorist group would follow their example and attempt to develop a biological weapon whose payload was Y. pestis bacteria”? I did not have an answer to the question, so I decided to conduct research whose objective was to prove or disprove the hypothesis: “It is likely that in the not too distant future, a terrorist group will utilize Y. pestis in an attack against a human population.”

In the historic literature there are many accounts of armies and armed bands having utilized Y. pestis for biological warfare (BW) purposes. The methods for waging BW were primitive, such as catapulting plague victims who were sick or had recently died and thus were infested by human fleas (Pulex irritans) that, in turn, carried Yersinia pestis (Y. pestis)1 into the encampments of enemies. After the plague victim’s body landed within the targeted area, the fleas would escape its lifeless host and seek living animals for their meals of blood. When successful, the flea’s bite would convey Y. pestis cells into the new host. However, no modern military has used such methods for disseminating Y. pestis among its enemies, nor are they likely to be so used in the future. For this reason, I chose not to delve into ancient military history but limit my consideration to two BW methods that have been used in the 20th century and, possibly, might again be used in the future. The first method is to disperse Y. pestis via a vector, for example human fleas such as P. irritans, amidst a targeted population. The second method involves dispersing Y. pestis cells as an aerosol onto the enemy’s troop formations or civilian populations.

This article has seven sections. First, I describe the pathogen Y. pestis and the three forms of the disease it causes. The second section contains a short history of plague vaccines, while the third section contains an even shorter history of therapeutics. The fourth, fifth, and sixth sections address the historical BW programs of, respectively, Japan, the United States (U.S.), and the Union of Soviet Socialist Republics (USSR). Of these countries, Japan and the USSR chose to weaponize Y. pestis and use it to arm biological weapons, while the US decided not to weaponize Y. pestis but did investigate methods to defend against plague. In the seventh and last section I discuss reasons why Y. pestis currently is considered a dangerous threat agent by both military and civilian entities that are responsible for protecting their populations from infectious diseases and consider future developments that may result in weapons based on Y. pestis becoming elements of national or terrorist arsenals. By doing the last, the stated hypothesis is supported or refuted.

Continue reading at the Institute for Defence Studies and Analyses

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