Q: Examination of sites are reported to have "trace" amounts of anthrax. If not
decontaminated, how long will the anthrax remain active? What are the
possibilities of "false positives" at these sites, and how is the baseline and
calibration of the tests used established?
Jack M. Goldstein
A: If traces of anthrax spores are not killed with bleach or exposure to
ultraviolet radiation, they can persist in a building for months or even years.
Because the spores tend to adhere tightly to surfaces, however, it is extremely
unlikely that trace amounts could be reaerosolized to cause inhalation anthrax.
Rapid preliminary tests for anthrax can result in false-positives, but
follow-up tests (involving culturing the anthrax bacteria) are highly
Q: In the 1950s and 1960s United States government scientists released bacteria
over U.S. cities. Even though the scientists claimed that the viruses were
harmless, doctors have records proving that many citizens became ill as a
result. Why hasn't the U.S. government made reparations to the citizens, and
how can we be certain that our own government has not and will not again dump
biological weapons on anyone.
A: The microbial agents released over U.S. cities during the biowarfare
experiments of the 1950s and 1960s were "simulant" bacteria such as Serratia
marescens, which do not harm healthy people but occasionally cause illness
in people with an impaired immune system. Although a cluster of cases of S.
marescens infection was reported in hospital patients following a
biowarfare simulant test in San Francisco, the evidence for a cause-and-effect
relationship was not clear-cut, and the U.S. government denied responsibility.
Testing of biowarfare simulants over populated areas ended in the 1960s.
Q: I understand that cowpox, which is much less virulent than smallpox, confers
immunity from smallpox. Considering the fact that there is not enough smallpox
vaccine to go around, would it be feasible, in an informed consent scenario, to
be prophylactically infected with cowpox? It would have the virtue of
decreasing the number of people who would require the vaccine if the need
San Francisco, CA
A: Cowpox virus was the original smallpox vaccine developed by Edward Jenner in
1796 [see Making Vaccines]. Since then, cowpox has been replaced as the
active ingredient of smallpox vaccine by a different but related virus known as
"vaccinia." Although vaccinia produces a harmless, localized infection in most
people, it can protect against the far more virulent disease caused by the
Q: Do the anthrax spores germinate when they come in contact with water, and is
it safe to flush these spores down the drain as is recommended when you are
A: Anthrax spores will only germinate in a moist, nutrient-rich environment
such as the interior of the human lung. Anthrax is not naturally transmitted
through water, and even if terrorists were to dump anthrax spores in an urban
reservoir, the spores would be killed by chlorination during the water
Q: My question is how effective would it be for the terrorists to disperse any
biological or chemical weapons from an airplane? I have heard that it can
actually break down the pathogen and make it essentially ineffective. Thank you
for your time.
A: Reports that some of the September 11th terrorists were
interested in crop dusters have raised concerns that the perpetrators were
planning to use such aircraft to spray biological agents over populated areas.
Standard crop-dusting equipment, however, would not be suitable for this
purpose without extensive modification. The reason is that a crop duster is
designed to spread a pesticide or fertilizer over a single field of crops,
while minimizing drift of the chemical over adjacent fields. In contrast,
someone seeking to disseminate a biological agent over a large target area
would want to maximize the drift of the agent downwind.
Q: How likely is it that an agent like smallpox, if used, will spread back to
the country of origin and the world? Do terrorists have to fear their own
A: Since smallpox (unlike anthrax) is contagious from person to person, it is
not a "targetable" weapon. Thus, an attacking country would run the risk that
the resulting epidemic might spread uncontrollably and eventually affect the
attacker's own population. Terrorists handling smallpox virus would also be at
great risk of infection themselves unless they were vaccinated, although some
fanatics might be prepared to die in carrying out an attack.
Q: Is it true that you can sterilize your mail by putting it in the microwave
for 30 seconds? Will that help if my envelope was contaminated in the
A: Microwaving letters is not an effective way of sterilizing mail. In fact,
such treatment could actually rupture an envelope containing anthrax spores and
contaminate the interior of the oven. Instead, any lettter that appears
suspicious should be sealed in a plastic bag and reported to the local health
Q: I am currently a junior at Skutt Catholic College Preparatory High School in
Omaha, Nebraska. I am doing an independent research study in my Accelerated
Physics class. I am trying to prove that the use of mass spectrometry/optics
will be a crucial detection mechanism in the war against biochemical warfare
What are your thoughts on this subject? Any related information would be
greatly appreciated. Thank you.
A: Mass spectrometry is a useful analytical technique for identifying chemical
warfare agents, as well as certain biological toxins (nonliving poisons
produced by living organisms, such as botulinum toxin or ricin).
Q: I was born in 1957. Weren't all the children in the U.S. immunized against
smallpox at that time? Would people who were immunized as children stand a
better chance of fighting off an exposure to smallpox now? Please explain if
different strains of smallpox are at issue and whether the vaccination
definitely "wears off" after a number of years. Thank you.
A: Vaccination against smallpox was mandatory for U.S. children before school
entry until 1972. People who were vaccinated once in childhood may retain some
residual immunity that would probably not protect them from infection entirely
but would make the disease somewhat milder. Those who were vaccinated two or
more times (such as military recruits or travelers to smallpox-endemic
countries in the 1960s or 1970s) should have a significantly higher level of
immunity. Smallpox vaccine protects against all known strains of the
Q: I know anthrax spores can live 100-odd years. But is there any way for us to
tell whether anthrax discovered on a post office sorting machine tomorrow is a
new incident (i.e., from a recent mailing, not from an older mailing that
wasn't discovered at that time)? Is there any way to tell how long anthrax
spores have been sitting on a surface, for example?
A: It is impossible to distinguish between anthrax spores deposited on surfaces
a few days apart. If the spores had been deposited on letter-sorting equipment
years earlier, it is likely that they would have caused detectable cases of
disease among postal workers.
Q: Do you believe our nation's agriculture may be threatened under the auspices
of economic sabotoge? If so, do you believe additional research may benefit
this as it has done with anthrax and botulism?
A: The U.S. Department of Agriculture is very concerned about the possibility
of "agroterrorism" as a means of economic warfare against the United States.
Indeed, a single outbreak of foot-and-mouth disease could shut down the
nation's entire beef exporting industry, inflicting severe economic damage on
ranchers and meat packers. Accordingly, further resarch on vaccines and other
control strategies for livestock disease is warranted.
Q: What does it mean to "weaponize" a germ?
A: The "weaponization" of a microbial pathogen or toxin involves several
dimensions. These include: (a) rendering the agent resistant to standard
antibiotic drugs; (b) freeze-drying and milling the agent into an extremely
fine powder, consisting of particles tiny enough to become readily airborne and
inhaled into the victims' lungs to cause infection; (c) stabilizing the agent
so that it will remain infectious for a longer period after release; and (d)
treating the powder with chemical additives that absorb moisture and reduce
clumping, so as to facilitate aerosolization.
Q: Why can't dogs sniff out bioweapons like they do drugs?
A: If a dried biological warfare agent is transported in a sealed container, it
will not give off any odor or other "signature" that could be detected by dogs
or by some mechanical detection device.