Environmental Engineering Reference
In-Depth Information
and variola minor, which causes a milder form of the disease resulting in under
1 percent fatalities among cases. The only remaining stocks of the variola virus
are currently being held in secure locations in the United States and Russia. The
WHO voted to postpone a decision on the remaining variola stocks until 2002,
raising the possibility of their misappropriation and use as weapons.
108
The sci-
entific community has requested that the available virus stocks be maintained
and no further action on the part of WHO has been taken. Some have ques-
tioned the grounds for maintaining smallpox stocks. The likelihood of a rebirth
of a vaccination program is minimal leading to the conviction that the only pur-
pose the stocks could serve is for bioweapons research. This raises the question
of accidental release, improper disposal of hazardous materials, and laboratory
mishandling.
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Variola virus satisfies a number of the prerequisites for an ideal
bioterror agent. Since immunization against smallpox was halted in 1976, fol-
lowing a successful worldwide eradication program that saw the last known case
of smallpox in 1977, a significant number of the U.S. population would be at
risk from a bioterrorism attack. Although individuals vaccinated prior to 1976
may retain immunity to smallpox, the level of protection is currently unknown.
Smallpox is generally fatal in about 30 percent of infections of unvaccinated
individuals.
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Given these uncertainties and the significant health risk of smallpox, the
United States and other countries are currently increasing the production of
smallpox vaccine. In the wake of concerns for the deployment of variola virus
in a bioterror attack, The Advisory Committee on Immunization Practices for-
mulated an interim smallpox release plan, guidelines and a revision of vaccine
recommendations in 2001 and reiterated recommendations in 2003.
102
However,
approximately 1 in 1 million people exhibit serious and potentially fatal com-
plications following vaccination. Thus, if the entire U.S. population were to be
vaccinated, we might expect 100 to 300 deaths from the vaccine. To avoid this
situation, one strategy that is being considered for a bioterrorism attack is to
limit vaccination to individuals who have come in contact with the initial (index
case) infected individual. Vaccination and training of primary health care work-
ers and physicians who are most likely to see the first cases in an attack will
also be an important aspect for countering the use of viruses and bacteria as
weapons.
Anthrax
Anthrax is a zoonotic disease caused by
Bacillus anthracis
, the facultatively
anaerobic, gram positive, nonmotile, endospore-forming bacillus isolated by
Robert Koch in 1877 and used by Koch to demonstrate for the first time the
relationship between an infectious agent and the etiology of disease. Many
domestic and wild animal species have been demonstrated to harbor the anthrax
bacillus. Three forms of the disease may be expressed and each is related to the
points of entry of the bacterial spores into the body: cutaneous, gastrointestinal,
and pulmonary.
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Cutaneous anthrax in humans occurs through handling of
