Viral hemorrhagic fevers

This chapter discusses viral hemorrhagic fevers (VHF), a group of acute systemic illnesses that classically involve fever, a constellation of initially nonspecific signs and symptoms, and a propensity for bleeding and shock. VHFs are caused by small, single-stranded, lipid-enveloped RNA viruses from four families: Arenaviridae, Bunyaviridae, Filoviridae, and Flaviviridae. Because the hemorrhagic fever viruses are zoonotic, a reservoir is constantly maintained in nature in mammals. The endemic area of any given VHF is restricted by the distribution of its natural reservoir and/or its arthropod vector, although the distribution of any virus is often less vast than that of its reservoir. Infection with a VHF is usually the result of inadvertent inoculation of virus-contaminated excreta into mucous membranes or broken skin, or through mosquito or tick bites.