357 - Viral Hemorrhagic Fevers

Abstract

Viral hemorrhagic fever is an acute systemic febrile syndrome caused by over 30 viruses from four different virus families. Microvascular instability with capillary leak and impaired hemostasis are the pathogenic hallmarks. The syndrome is characterized by a short incubation period (usually 1 to 2 weeks) followed by a rapidly progressive illness usually lasting no longer than 2 weeks. Initial signs and symptoms are usually nonspecific and include fever, headache, and myalgia, followed rapidly by gastrointestinal symptoms and, in some cases, rash and neurologic involvement. Severe cases develop hemodynamic instability, bleeding, shock, and multiorgan system failure. Mortality rates range from less than 1 to over 80% depending on the specific infecting virus. The causative viruses are zoonotic, with endemic areas limited to the distribution of their mammalian reservoirs and/or arthropod vectors. Imported cases are rare. The nonspecific clinical manifestations of the syndrome make clinical diagnosis of single cases extremely difficult. Viral hemorrhagic fever should be considered in febrile patients with a compatible clinical syndrome and history of travel and exposure. Although many hemorrhagic fever viruses may be spread person-to-person, secondary attack rates are generally low when routine universal precautions are maintained. For added safety, specialized viral hemorrhagic fever precautions are warranted when there is a confirmed case or high index of suspicion. Treatment of viral hemorrhagic fever is generally supportive. The antiviral drug ribavirin may be indicated for a few viral hemorrhagic fevers, although more definitive evidence of efficacy is needed.