Chapter 263 Other Viral Hemorrhagic Fevers
Etiology
Six of the viral hemorrhagic fevers are caused by arthropod-borne viruses (arboviruses) (Table 263-1). Four are togaviruses of the family Flaviviridae: Kyasanur Forest disease, Omsk, dengue (Chapter 261), and yellow fever (Chapter 262) viruses. Three are of the family Bunyaviridae: Congo, Hantaan, and Rift Valley fever (RVF) viruses. Four are of the family Arenaviridae: Junin, Machupo, Guanarito, and Lassa viruses. Two are of the family Filoviridae: Ebola and Marburg viruses. The Filoviridae are enveloped, filamentous RNA viruses that are sometimes branched, unlike any other known virus.
MODE OF TRANSMISSION | DISEASE | VIRUS |
---|---|---|
Tick-borne | Crimean-Congo HF* | Congo |
Kyasanur Forest disease | Kyasanur Forest disease | |
Omsk HF | Omsk | |
Mosquito-borne† | Dengue HF | Dengue (four types) |
Rift Valley fever | Rift Valley fever | |
Yellow fever | Yellow fever | |
Infected animals or materials to humans | Argentine HF | Junin |
Bolivian HF | Machupo | |
Lassa fever* | Lassa | |
Marburg disease* | Marburg | |
Ebola HF* | Ebola | |
Hemorrhagic fever with renal syndrome | Hantaan |
* Patients may be contagious; nosocomial infections are common.
† Chikungunya virus is associated infrequently with petechiae and epistaxis. Severe hemorrhagic manifestations have been reported in some cases.
Epidemiology and Clinical Manifestations
With some exceptions, the viruses causing viral hemorrhagic fevers are transmitted to humans via a nonhuman entity. The specific ecosystem required for viral survival determines the geographic distribution of disease. Although it is commonly thought that all viral hemorrhagic fevers are arthropod borne, 7 may be contracted from environmental contamination caused by animals or animal cells or from infected humans (see Table 263-1). Laboratory and hospital infections have occurred with many of these agents. Lassa fever and Argentine and Bolivian hemorrhagic fevers are reportedly milder in children than in adults.