How Great a Threat?
An interview with bioterrorism expert Jonathan B. Tucker.

By Kathryn Jean Lopez, NRO executive editor
October 15, 2001 8:25 a.m.

Kathryn Jean Lopez: Are we all getting a little overexcited about the threat of anthrax?

Jonathan B. Tucker: Yes, the level of public anxiety about anthrax appears to be disproportionate to the current threat. To date, the various anthrax incidents around the country have produced one fatal case of inhalation anthrax — by far the most deadly form of the disease — and one or two cases of cutaneous (skin) anthrax, which is eminently treatable if recognized within a reasonable amount of time. All the other incidents have involved either exposure to anthrax spores in doses too low to cause infection, or hoaxes involving harmless powders.

Although inhalation anthrax is extremely serious, it requires the victim to inhale at least 8,000 spores of the bacterium. Direct contact with powdered anthrax spores in an envelope is unlikely to cause inhalation anthrax but rather a much less serious skin infection.

Finally, it is important to remember that anthrax is not contagious from person to person, and that all the incidents to date have involved low-tech methods of dissemination affecting limited areas and numbers of people. The ability to cultivate small amounts of anthrax spores and sent them through the mail does not necessarily translate into the ability to stage a mass-casualty attack with anthrax, which would be technically far more difficult.

Lopez: You've written about smallpox — how much of a danger is there that terrorists could use smallpox as a method of terror? Is it easy enough to spread?

Tucker: The smallpox virus is generally considered a "worst-case" bioterrorist threat agent because it is infectious through the air, kills about a third of its victims, and is contagious from person to person. But terrorists would have a hard time obtaining the virus because smallpox was eradicated from the human population by means of a global vaccination campaign during the 1960s and '70s, and the last reported case in the world was in 1978. Samples of the smallpox virus currently exist only in a few laboratories. Nevertheless, in addition to two secure repositories of the virus located in the United States and Russia, circumstantial evidence suggests that undeclared stocks of smallpox virus may exist in countries of concern such as Iraq and North Korea.

If terrorists were to get their hands on the virus (probably from a state sponsor), they would have to cultivate it and then find some means of dissemination. The simplest method would be for suicide terrorists to infect themselves with the virus and spread it in crowds, but even terrorists willing to die instantly in a blaze of glory might think twice about suffering the torments and disfigurement of smallpox. Other delivery methods would be technically challenging. Still, although the risk of a terrorist attack with smallpox is low, it is not zero, and the disastrous consequences of an uncontrolled epidemic mean that the U.S. government must err on the side of caution.

At present, the federal government is taking two steps to reduce the nation's vulnerability to smallpox: testing to determine if the roughly 7.5 million doses of smallpox vaccine currently available could be diluted safely to provide as many as 75 million doses, and accelerating production of 40 million additional doses of the vaccine so that they are available by the end of next year. Even if a large amount of smallpox vaccine were available today, however, it would not be desirable to vaccinate the general population prophylactically because of the risk of serious complications, particularly in people who are HIV-positive or have some other form of immune-system impairment.

Lopez: Regarding smallpox, it is, of course, contagious. Are the vaccinations we all got as kids any good against it? Is it curable if contracted?

Tucker: Actually, most Americans alive today were never vaccinated against smallpox or no longer have effective immunity. Until 1971, it was mandatory for U.S. children to be vaccinated before school entry, even though the last case of smallpox in the United States was in 1949. After 1971, however, the government halted routine vaccination, having assessed that the risk that smallpox could be imported into the United States from a country where it was still endemic was lower than the risk of side effects associated with smallpox vaccine, which caused occasional deaths or serious complications in people with immune-system impairments, eczema, and even in a few healthy people. Moreover, a single smallpox vaccination did not provide life-long protection; instead, the level of immunity diminished gradually over a period of about ten years unless it was "boosted" by a second vaccination, which provided much longer-lasting protection. Thus, Americans who were vaccinated only once as children, or who were never vaccinated, are susceptible to infection if the disease were ever to reappear.

Vaccination can prevent smallpox if administered up to four days after exposure but before the appearance of symptoms, but no drug treatment is available once fever and skin rash develop. Even without treatment, however, victims of smallpox would have a two-in-three chance of surviving the disease.

Lopez: Do you think this could all be a distraction? That, perhaps, there's another threat that we are even more unprepared for on the horizon?

Tucker: That's possible, of course. Even if the anthrax incidents are linked to the September 11 attacks, which is far from certain, they could well be a diversionary tactic. It's very hard to put oneself in the terrorists' shoes and anticipate their next move. Given the relatively low-tech nature of the September 11 attacks and the fact that the terrorists used our own technology against us by converting passenger airliners into guided missiles, one possible scenario might be the sabotage of a chemical plant or rail cars transporting a hazardous chemical, creating a toxic cloud that could expose thousands of people downwind. Indeed, in December 1984, an accident at a Union Carbide plant in Bhopal, India, released 50,000 pounds of methyl isocyanate gas, killing about 2,500 people and seriously injuring about 10,000.

Lopez: Is the U.S. prepared for a major city being hit by one of these bioterror threats?

Tucker: Although the United States is not entirely unprepared for bioterrorism, we are — in the words of Senator Bill Frist (R., Tenn.) — "underprepared." Federal agencies such as the Centers for Disease Control have great depth of expertise on bioterrorism threats, and large amounts of antibiotics and other therapeutic drugs have been stockpiled, but a number of serious gaps remain in the nation's defenses. The main weakness is at the level of state and local health departments, which would provide the first line of defense against a bioterrorist attack by detecting an unusual outbreak of disease early on, while it is still treatable or readily containable.

To fill these gaps, it will be essential to: (1) train doctors and nurse-practitioners so that they can recognize unusual diseases such as anthrax, plague, and smallpox, which they would not normally encounter in their medical practice; (2) improve staffing and communications at city, county, and state health departments so that physicians can report suspicious cases by phone or e-mail on a 24/7 basis; (3) increase the number of clinical laboratories around the country capable of diagnosing bioterrorist threat agents; and (4) help hospitals to develop emergency-response plans for dealing with a range of attack scenarios.

Fortunately, Congress appears to have recognized the urgency of the bioterrorism threat in the wake of the recent attacks, and a substantial increase in funding to strengthen the U.S. public-health system now appears likely.

Lopez: Is the government doing what it should in terms of warning and reassuring Americans?

Tucker: There is considerable room for improvement. The federal government needs to develop a coherent strategy for informing the public about the threat of bioterrorism without spreading panic or spawning false rumors. Thus far, various federal agencies have provided conflicting information or have made vague statements that have fostered unhelpful speculation. More generally, the government has failed to reassure the public by putting the threat of bioterrorism into perspective compared with other risks of daily life. Despite all the anxiety, the average American is probably at greater risk of death or injury from driving on the highway than from exposure to anthrax.

Lopez: What should the average American do besides watch their mail to prepare for or protect against any potential bioterror threat?

Tucker: Beyond urging members of Congress to increase spending on disease surveillance and other public-health measures for combating bioterrorism, Americans should remain vigilant and inform the police of any suspicious activities they might observe, such as someone spraying a fine mist from a building, a vehicle, or in an enclosed space such as a subway station.

Purchasing a gas mask is probably not a good investment because a bioterrorist attack would probably occur covertly and without warning. Because the agent cloud would be invisible and odorless, individuals would not know when to don their masks to protect them from exposure. Thus, unless the mask were worn at all times, it would probably provide little protection. (Masks also vary markedly in quality and effectiveness against different threats, must be fitted to the user's face to ensure an airtight seal, and require training in proper use and maintenance.)

Individuals should also refrain from stockpiling antibiotics or taking them prophylactically because of the risk of side effects, the fact that overuse of antibiotics fosters the emergence of drug-resistant bacterial strains, and the concern that hoarding of antibiotics could deplete the national supply available in the event of a real attack.

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