Question 1
Smallpox is considered a serious potential biological weapon, whereas anthrax has been successfully used as one. Compare and contrast their potential with regard to the criteria for assessing biological threats.Question 2
The dengue and Ebola viruses cause hemorrhagic fevers. Evaluate their threat levels as select agents using the criteria in the textbook, and decide whether they pose significant risk as biological weapons.Answer 1
The smallpox virus causes serious illness with moderate to high fatality rates. The virus is highly contagious by contact and aerosols, and it is contagious before clear signs appear. The virus can persist on fomites and infect persons who come in contact with them. Although a vaccine exists, the majority of the world's population is currently unvaccinated. Consequently, once released, the virus will spread rapidly. However, there is no natural source for the virus, so a person or persons intent on using it as a weapon would have to have special access and facilities to be able to produce much virus. Additionally, post-exposure vaccination is effective in producing immunity, so the resulting epidemic could be controlled once recognized.Answer 2
Impact: Dengue virus can cause serious debilitating illness in adults but is only occasionally fatal, while the fatality rate among children is much higher. On the other hand, exposure to a different strain (there are 5) results in more severe disease. The public health impact could be increased by successive release of different strains into a susceptible population. People in areas where dengue viruses are endemic may have natural immunity. Delivery: Dengue viruses are transmitted by mosquitoes. An initial release of infected mosquitoes could result in many illnesses, but if the normal vector is not endemic to the area the disease would not continue to spread. Spread would also be seasonal in most temperate areas. Public perception and preparedness: In temperate zone developed countries there is not much awareness of dengue, so initially people might not perceive that they were under attack. In the 100 or so tropical to subtropical countries where dengue occurs the public would recognize the outbreak more quickly. There are no specific treatments, and vaccines are in development but not yet available. Dengue virus is not an "ideal" biological weapon, but has some potential.