Disease Information for Viral hemorrhagic fevers: Definition

A diverse group of disorders from several virus families (Filoviridae, Arenaviridae, Bunyaviridae, and Flaviviridae) and immunologic responses to them; The common clinical features include high fever, leukopenia, and altered mental status combined with a hemorrhagic diathesis; Marked toxicity and death may occur; Modes of transmission are similarly diverse; Dengue and yellow fever are due to flaviviruses that are transmitted by mosquitoes, while Omsk hemorrhagic fever and Kyasanur Forest disease are due to tick-borne flaviviruses; Lassa fever is rodent-associated, as are Junin hemorrhagic fever and other diseases due to New World Arenaviridae; Ebola fever and Marburg fever are due to filoviruses with unknown vectors; The bunyaviruses include the tick-borne Crimean-Congo hemorrhagic fever and the mosquito-borne Rift Valley fever (a major outbreak in Saudi Arabia in 2000–2001 involved over 800 persons), while the infections due to hantaviruses are associated with rodent exposure; The Nipah virus in Malaysia is a zoonotic paramyxovirus that does not cause hemorrhagic fever but instead causes a primarily encephalitic infection; Most cases are associated with a history of contact with pigs; Flying foxes appear to be the natural host; Persons who present with symptoms compatible with those of hemorrhagic fever and who have traveled from a possible endemic area should be isolated for diagnosis and symptomatic treatment; Diagnosis may be made by growing the virus from blood obtained early in the disease, by reverse transcriptase PCR, or by demonstration of a significant specific fourfold or greater rise in antibody titer; These tests are generally available only through the Centers for Disease Control and Prevention; Isolation is particularly important because diseases due to some of these agents, such as Ebola virus, are highly transmissible and carry a mortality rate of 50–90%;

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