Worst-case scenarios abound for bioterror

While there is broad consensus about the need for heightened awareness and education about the threat of bioterrorism, discussions about preparedness and response can become somewhat overwhelmed by the sheer horror of the various scenarios. "You can spin worst-case scenarios until you kind of slink away and need a glass of wine," says Tara O’Toole, MD, MPH, senior research fellow at the Center for Biodefense Studies at Johns Hopkins University in Baltimore.

For example, while smallpox is generally considered the worst-case pathogen, a bioweapon that aerosolized the plague bacteria Yersinia pestis would create pneumonic plague, an airborne transmissible disease. While antibiotic treatment would be an option, the biodefense center reports that 50 kg of Y. pestis aerosolized over a city of 5 million would result in 150,000 infections, at least half of which would require hospitalization, and some 36,000 deaths.1

"Anything contagious, obviously, would be extremely worrisome in our highly mobile society," O’Toole tells Hospital Infection Control. "[Smallpox] is certainly one of the scarier propositions. Inhalation plague would be no day at the beach either — probably somewhat less contagious, but it is still transmissible, and would also kill you very effectively." In addition, both plague and anthrax (Bacillus anthracis) would likely be easier to obtain by a terrorist group or rogue government than smallpox. While secondary infection would not be a concern with anthrax — and there is a vaccine for the military — the biodefense center cites government projections that estimate that the release of 100 kg of the pathogen over Washington, DC, would result in a minimum of 130,000 deaths. In a real-world example, when aerosolized anthrax spores were accidentally released in 1979 from a bioweapons facility in the former Soviet Union, 68 of the 79 people infected died.1 While one could academically argue that intentional release of an infectious agent like smallpox or plague is a more dire scenario, the aftermath of mass anthrax exposure would be grim.

Those known or suspected to be exposed to anthrax would probably wait in long "Auschwitzian" lines of people waiting to get chest X-rays, says Allan J. Morrison Jr., MD, MSc, FACP, health care epidemiologist for the four-hospital Inova Health System in Washington, DC. There would be little hope or medical options for those who showed radiographic evidence of anthrax infection, he says. "Basically, no resources are going to be spent on you because you are not going to make it — with a 90% likelihood. Even if you feel fine," says Morrison, a former member of the U.S. Army Special Forces. "If you have a normal chest X-ray, then you go into line B,’ where resources would be expended and antibiotics would be used," he says. "I think most people would accept that algorithm, as fiercely horrifying as it is. That is the fact. So for a non-transmissible agent like anthrax, setting up mass radiographic screening is the first step, and managing the patients who are in the treatment cohort is really where your preparedness comes in. How can you obtain, dispense, and coordinate treatment?"

Moreover, while the wild forms of the various bioterrorism pathogens are sufficiently nightmarish, there is, unfortunately a worst case still: genetically engineered infectious agents. For example, researchers in Moscow have created a recombinant strain of anthrax, raising the possibility that current vaccine efficacy could be undermined.2 The advances of bioengineering will only continue, creating the possibility that scientists will find ways to create bioweapons that elude known postexposure treatments and vaccines, says O’Toole.

"The technology to make these weapons is quite available," she says. "If the will and the money and the talent come together to do evil things, then it is a real possibility. The health care community has got to awaken to this threat and figure out a responsible way of dealing with the dark side of modern biology."

References

1. Center for Civilian Biodefense Studies. John Hopkins University. http://www.hopkins-biodefense.org/pages/ response/agent.html.

2. Pomerantsev AP, Staritsin NA, Mockov Yv, et al. Expression of cereolysine AB genes in Bacillus anthracis vaccine strain ensures protection against experimental hemoly tic anthrax infection. Vaccine 1997; 15:1,846-1,850.