OTHER VIRAL AGENTS
A variety of other viruses have been considered as possible biowarfare agents, but none seems to have achieved a consensus. As noted above, viruses need host cells and so most viruses are difficult to culture in large amounts. In addition, many virus particles are unstable during storage.
Filoviruses , including Ebola and Marburg viruses, are a family of negative single-stranded RNA viruses that form long, thin filaments. The virus spreads through the blood system and causes vomiting of blood in doomed patients. Ebola virus has caused outbreaks in Sudan and Zaire with 80% to 90% fatality. Nonetheless, many closely related virus strains exist that are nowhere near so virulent. For example, in 1989, an Ebola outbreak occurred among monkeys in a research facility in Reston, Virginia. The monkeys, long-tailed macaques, had been freshly imported from the Philippines. Although the incident received a great deal of publicity, the Reston strain ofmEbola virus was not even lethal to humans. Furthermore, most filoviruses are relatively difficult to catch by casual exposure, and transmission usually requires substantial exposure to infected body fluids. In practice this makes them relatively poor choices for biowarfare agents.
Dengue fever and yellow fever are both caused by members of the Flavivirus family. Yellow fever is frequently lethal, whereas dengue is rarely fatal, but is highly painful and incapacitates its victims for several days. However, both are spread by insect bites, which would greatly impede their possible use as biological weapons.
Lassa fever is an emerging virus disease, which appeared in the Lassa River region of Nigeria in the late 1960s. Lassa is a member of the Arenavirus family and contains segmented singlestranded RNA. Rodents spread the virus. Lassa virus has extremely high mortality and was considered briefly as a possible biowarfare agent.