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Viral hemorrhagic fever is
a severe, sometimes fatal, multisystem syndrome characterized by
diffuse vascular damage and dysregulation; hemorrhage does not necessarily
occur; when it does, it is rarely a sufficient cause for demise.
The etiologic agents of this syndrome are zoonotic, lipid-enveloped
ribonucleic acid (RNA) viruses and include dozens of members from
4 families of viruses: arenaviruses, bunyaviruses, filoviruses,
and flaviviruses (Table 307-1). These agents
are localized geographically and are associated with specific vector
hosts or reservoirs,1-5 although imported cases
and infections caused by laboratory accidents and nosocomial transmission
can occur outside their respective ranges.6 The
diseases they cause are either endemic or episodic with both annual
cycles and longer secular trends. Some are associated with high
lethality and potential for person-to-person transmission. The challenges
for clinicians evaluating suspect cases are to exclude more likely
conditions that are potentially life-threatening and treatable (especially
malaria and typhoid fever); narrow the differential diagnosis based
on the travel history; institute appropriate precautions for the
diseases in the narrowed differential that are associated with person-to-person
transmission; and seek expert guidance for diagnostic confirmation
and treatment guidelines.
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