Viral Hemorrhagic Fever

Epidemiology:

-No endemic hemorrhagic viruses in US


Etiology

(all are small RNA viruses with lipid envelopes)

1) Marburg virus: weaponized by USSR/may be associated with possible bioterrorism
2) Ebola virus: weaponized by USSR/may be associated with possible bioterrorism
3) Lassa virus: weaponized by USSR
4) Junin virus: weaponized by USSR
5) Yellow fever virus: weaponized by US
-Transmitted by mosquitoes
-Acquired in rural tropical and subtropical areas of Africa, South America, and Panama
6) Rift valley fever virus: weaponized by US
7) New World virus: may be associated with possible bioterrorism
8) South American virus: may be associated with possible bioterrorism
9) Machupo virus:


Physiology

  • Natural transmission: contact with excreta of infected rodents or arthropod vectors (humans are incidental hosts)
  • Reservoir/vector for Marburg and Ebola viruses is unknown
  • Incubation: 2-21 days

Diagnosis

  • CBC
    • Leukopenia
    • Anemia: due to bleeding or hemo-concentration
    • Thrombocyto-penia:
      CHEM:
      -Elevated LFT’s
      PT/PTT: elevated
      Diagnosis: needs to be performed by Level D labs at the CDC or USAMRIID

Clinical Presentation

  • Fever

    – Pleural Effusion (see [[Pleural Effusion-Exudate]]): has been reported with Lassa Virus

Symptoms/signs: may be confused with meningococcemia/ differentiation of viruses on clinical grounds is difficult/any suspicion should be reported as a bioterrorism event
1) High fever:
2) Headache:
3) Arthralgias/myalgias:
4) Abdominal pain:
5) Conjunctivitis:
6) Pharyngitis:
7) Petechiae/purpura of mucosa and conjunctiva:
8) GI/urinary tract hemorrhage:
9) DIC: common

Prognosis:
-Varies by virus: case-fatality rate varies from 0-90%

Complications:
1) Multi-organ failure:
2) Death:


Treatment

Supportive:
-Steroids: not effective

Ribavirin: useful for Junin, Lassa, Machupo (arenaviruses) if given within first 7 days of symptoms

Junin virus vaccine: investigational
-Live-attenuated vaccine

Yellow fever virus vaccine (live-attenuated):
-Generally considered to be safe (although small number of severe vaccine-related adverse reactions in 1990’s): risk of adverse reaction is 1/400k
–Higher risk of adverse reactions in elderly
-Certain endemic countries require proof of vaccination for entry
-Booster required q10 yrs
-Contraindications: pregnant, significantly immunosuppressed, <9 mo old

Post-exposure prophylaxis: ribavirin may be used for Junin, Lassa, Machupo viruses (arenaviruses)
-Follow temperature for signs of fever

Infection control: respiratory and contact precautions
-Contagious to close contacts and health care workers
-Respiratory transmission is infrequent


References

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