Smallpox
as a Weapon
Category
A Agent
Variola
virus is classified by the Center for Disease Control and Prevention
as a Category A bioterrorism agent. Most agents in category A can
cause infection by aerosol transmission, affect highly susceptible
civilian populations, have a high morbidity and mortality, and
are difficult to diagnose and/or treat. Some are transmitted from
person to person. Smallpox has all of these characteristics. (19:4)
A comprehensive
review of the problems posed by biological terrorism and warfare
has been published. Four observations deserve special note. (7:2) Biological
terrorism is more likely than ever before and far more threatening
than either explosives or chemicals. Official actions directed
at the threat to the civilian population have been only marginally
funded and minimally supported. Preventing or countering bioterrorism
will be extremely difficult. Recipes for making biological weapons
are now available on the Internet, and even groups with modest
finances and basic training in biology and engineering could develop,
should they wish, an effective weapon at little cost. Detection
or interdiction of those intending to use biological weapons is
next to impossible. Looking at the ease of production, infection
rates, and deadliness, both anthrax and smallpox seem the most
likely weapons of choice for a serious assailant. (6:23)

Smallpox represents
a serious threat to civilian populations because of its case-fatality
rate of 30% or more among unvaccinated persons and the absence
of specific therapy. (9:1) An aerosol release
of variola virus would disseminate widely, given the considerable
stability of the orthopoxviruses in aerosol form and the likelihood
that the infectious dose is very small. Moreover, during the 1960s
and 1970s in Europe, when smallpox was imported during the December
to April period of high transmission, as many as 10 to 20 second-generation
cases were often infected from a single case. (9:3)
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