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Public Health - Seattle & King County

Viral Hemorrhagic Fever advisories and resources

Epidemiology and microbiology
Report all suspected cases of Viral Hemorrhagic Fevers immediately to Public Health - Seattle & King County by calling 206-296-4774.
Virus family
Geographic occurrence of natural disease
Reservoir or vector
Incubation period
Machupo (Bolivian hemorrhagic fever)

Junin (Argentine hemorrhagic fever)

Guanarito (Venezuelan hemorrhagic fever)

Sabia (Brazilian hemorrhagic fever)

South America
7-16 days
Lassa Fever
West Africa
5-16 days
Crimean-Congo HF
Crimea, parts of Africa, Europe, and Asia
3-12 days
Rift Valley Fever
2-6 days
Diverse areas
Usually 2-4 weeks
Ebola Hemorrhagic Fever
2-21 days
Marburg Hemorrhagic Fever
2-14 days
Yellow Fever
Tropical Africa, Latin America
3-6 days
Dengue Fever
Tropical areas
3-14 days
Kyansur Forest Disease
2-9 days
Omsk Hemorrhagic Fever
  • Viral hemorrhagic fevers (VHF) are caused by a group of single-stranded RNA viruses from four families: Arenaviruses, bunyaviruses, filoviruses, and flaviviruses.
  • Humans are infected via the bite of an infected arthropod, inhalation of rodent excreta, or contact with infected animal carcasses.
  • Person-to-person transmission is possible with several agents, primarily through blood or body fluid exposure, and rarely, via airborne transmission.

Viral Hemorrhagic Fevers and Bioterrorism

  • Agents of concern for potential use as a biological weapon include the arenaviruses, filoviruses, hantaviruses, tick-borne hemorrhagic fever viruses and yellow fever.
Clinical presentation
  • All agents have an initial febrile prodrome with non-specific symptoms: headache, malaise,
  • fatigue/exhaustion, arthralgia, myalgia, nausea, dizziness, non-bloody diarrhea.
  • Clinical signs reflect vascular involvement with increased capillary permeability.
  • Ebola, Marburg, Rift Valley fever, and Crimean-Congo hemorrhagic fever viruses can cause disseminated intravascular coagulation (DIC); other viruses generally do not.
  • Illness onset is typically abrupt with filoviruses, flaviviruses, and Rift Valley fever, and more insidious with arenaviruses.
  • A maculopapular rash appears about five days after onset of illness caused by filoviruses.
  • Jaundice may be prominent in filovirus infections, Lassa fever, Rift Valley fever, and yellow fever.
  • Meningoencephalitis can occur in Rift Valley fever, Kyasunar Forest disease, and Omsk hemorrhagic fever.
  • Severe exudative pharyngitis is a characteristic early feature of Lassa fever.

Contact Public Health for patients with suspected VHF and the following clinical criteria:

  • Fever (101ºF) for less than three weeks,
  • Severe illness and no predisposing factors for hemorrhagic manifestations,
  • And at least two of the following hemorrhagic symptoms: hemorrhagic or purple rash, epistaxis, hematemesis, hemoptysis, blood in stools, other, and no established alternative diagnosis.
  • Evaluation should include a travel history and inquiry about exposure to ticks, mosquitoes, animals, and ill persons.
  • Laboratory diagnostic tests (blood/serum and other body fluids) are performed at public health labs.
    • Antigen detection by antigen-capture ELISA
    • Serology
    • RT-PCR
    • Immunohistochemistry
    • Electron microscopy
    • Viral isolation (performed at CDC)
Infection control
  • Airborne and contact precautions should be followed by all health care, environmental, and laboratory workers when VHF is suspected.
  • Patients should be placed in a negative pressure room and dedicated medical equipment used, if available.
  • Patients recovering from an arenavirus or filovirus infection should refrain from sexual activity for three months post-recovery.
  • Treatment is primarily supportive.
    • Correct coagulopathies as needed.
    • Avoid anticoagulant therapies, anti-platelet drugs, and intramuscular injections.
    • Maintain fluid and electrolyte balance.
  • Ribavirin may be available under an investigational new drug protocol for patients with arenavirus or bunyavirus infection.
  • Refer to the CDC's Bioterrorism website for current treatment and prophylaxis guidelines.
  • Persons exposed to VHF should be monitored for fever or hemorrhagic symptoms for 21 days post-exposure.
  • Ribavirin may have a role in the prophylaxis of symptomatic persons exposed to arenaviruses or bunyaviruses.
  • The only vaccine currently commercially available for VHF is a live-virus vaccine for yellow fever vaccine.
    • Recommended for travelers to endemic areas of South America and Africa and laboratory personnel.
    • Not useful for post-exposure prophylaxis because the time-to-immunity post-vaccination (10 days) is longer than the disease incubation period (three to six days).
  • Vaccines against Argentine hemorrhagic fever and Rift Valley fever are available as investigational new drugs, and research is underway to develop vaccines against other VHF viruses.
External websites