Viral hemorrhagic fever

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Viral haemorrhagic fevers
)
"VHFS" redirects here. For the former military installation in Virginia, see Vint Hill Farms Station.

Viral hemorrhagic fever
Other namesviral haemorrhagic fever
Infectious disease

Viral hemorrhagic fevers (VHFs) are a diverse group of animal and human

Ebola virus
, can cause severe, life-threatening disease.

Signs and symptoms

Signs and symptoms of VHFs include (by definition) fever and bleeding:

The severity of symptoms varies with the type of virus. The "VHF syndrome" (capillary leak,

dengue or Rift Valley fever
.

Causes

Five families of RNA viruses have been recognised as being able to cause hemorrhagic fevers.[citation needed]

  • The family
    Whitewater Arroyo virus
    hemorrhagic fevers.
  • The former family Bunyaviridae includes

The pathogen that caused the

cocoliztli epidemics in Mexico of 1545 and 1576 is still unknown, and the 1545 epidemic may have been bacterial rather than viral.[2][3]

Pathophysiology

Different hemorrhagic fever viruses act on the body in different ways, resulting in different symptoms. In most VHFs, it is likely that several mechanisms contribute to symptoms, including liver damage,

diapedesis and coagulation deficiency. From the vascular perspective, the virus will infect vascular endothelial cells, leading to the reorganization of the VE-cadherin catenin complex (a protein important in cell adhesion). This reorganization creates intercellular gaps in endothelial cells. The gaps lead to increased endothelial permeability and allow blood to escape from the vascular circulatory system.[citation needed
]

The reasons for variation among patients infected with the same virus are unknown but stem from a complex system of virus-host interactions. Dengue fever becomes more virulent during a second infection by means of antibody-dependent enhancement. After the first infection, macrophages display antibodies on their cell membranes specific to the dengue virus. By attaching to these antibodies, dengue viruses from a second infection are better able to infect the macrophages, thus reducing the immune system's ability to fight off infection.[citation needed]

Diagnosis

Definitive diagnosis is usually made at a reference laboratory with advanced

liver enzymes, and reduced blood clotting ability measured as an increase in both the prothrombin (PT) and activated partial thromboplastin times (PTT). The hematocrit may be elevated. The serum urea and creatine may be raised but this is dependent on the hydration status of the patient. The bleeding time tends to be prolonged.[citation needed
]

Prevention

Main article: Prevention of viral hemorrhagic fever

With the exception of yellow fever vaccine and Ebola vaccines, vaccines for VHF-associated viruses are generally not available. Post-exposure prophylactic (preventive) ribavirin may be effective for some bunyavirus and arenavirus infections.[4][5]

VHF isolation guidelines dictate that all VHF patients (with the exception of dengue patients) should be cared for using strict contact precautions, including hand hygiene, double gloves, gowns, shoe and leg coverings, and face shield or goggles. Lassa, CCHF, Ebola, and Marburg viruses may be particularly prone to

nosocomial (hospital-based) spread. Airborne precautions should be utilized including, at a minimum, a fit-tested, HEPA filter-equipped respirator (such as an N95 mask), a battery-powered, air-purifying respirator, or a positive pressure supplied air respirator to be worn by personnel coming within 1.8 meter (six feet) of a VHF patient. Groups of patients should be cohorted (sequestered) to a separate building or a ward with an isolated air-handling system. Environmental decontamination is typically accomplished with hypochlorite (e.g. bleach) or phenolic disinfectants.[6]

Management

Medical management of VHF patients may require intensive supportive care. Antiviral therapy with intravenous

U.S. Food and Drug Administration (FDA). Interferon may be effective in Argentine or Bolivian hemorrhagic fevers (also available only as IND).[citation needed
]

Epidemiology

Biowarfare potential

The VHF viruses are spread in a variety of ways. Some may be transmitted to humans through a respiratory route.[citation needed] The virus is considered by military medical planners to have a potential for aerosol dissemination, weaponization, or likelihood for confusion with similar agents that might be weaponized.[15][16]

See also

References

  1. PMID 23028323
    .
  2. ^
    PMID 11971767
    .
  3. ^ "500 years later, scientists discover what probably killed the Aztecs". The Guardian. Agence France-Presse. 2018-01-16.
  4. PMID 30124196.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  5. PMID 21122249.{{cite journal}}: CS1 maint: multiple names: authors list (link
    )
  6. U.S. Army Medical Institute of Infectious Diseases. pp. 143–44. Archived from the original
    (PDF) on 2007-06-09. Retrieved 2007-06-09.
  7. ^ "Was the Huey Cocoliztli a Haemorrhagic Fever?" (PDF). Archived from the original (PDF) on 2010-06-17. Retrieved 2010-07-25.
  8. ^ Indigenous Hemorrhagic Fever and The Spanish Conquest
  9. PMID 11304065. Archived from the original
    (PDF) on 2007-03-20. Retrieved 2006-12-04.
  10. ^ "Epidemics in New Spain". Archived from the original on 2010-06-14. Retrieved 2010-07-25.
  11. PMID 16775337
    .
  12. PMID 8964060
    .
  13. ISBN 0-470-09000-6
    .
  14. PMID 19478873
    .
  15. ^ Woods 2005, p. 145
  16. ISBN 978-1555811976
    .

External links
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