Viruses of the Bunya- and Togaviridae families: potential as bioterrorism agents and means of control.

When considering viruses of potential importance as tools for bioterrorism, several viruses in the Bunya- and Togaviridae families have been cited. Among those in the Bunyaviridae family are Rift Valley fever, Crimean-Congo hemorrhagic fever, hanta, and sandfly fever viruses, listed in order of priority. Those particularly considered in the Togaviridae family are Venezuelan, eastern and western equine encephalitis viruses. Factors affecting the selection of these viruses are the ability for them to induce a fatal or seriously incapacitating illness, their ease of cultivation in order to prepare large volumes, their relative infectivity in human patients, their ability to be transmitted by aerosol, and the lack of measures available for their control. Each factor is fully considered in this review. Vaccines for the control of infections induced by these viruses are in varying stages of development, with none universally accepted to date. Viruses in the Bunyaviridae family are generally sensitive to ribavirin, which has been recommended as an emergency therapy for infections by viruses in this family although has not yet been FDA-approved. Interferon and interferon inducers also significantly inhibit these virus infections in animal models. Against infections induced by viruses in the Togaviridae family, interferon-alpha would appear to currently be the most useful for therapy.