Updated: 7/17/2018

Yellow Fever Virus

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Snapshot
  • A 40-year-old man presents to a hospital after flying from sub-Saharan Africa. He had been on a safari and had sustained multiple mosquito bites. He had not gotten his necessary vaccines, as the trip was planned last-minute. For the past 2 days, he has had fevers, chills, myalgias, and some vomiting. After landing, he had an episode of bloody vomiting. On physical exam, he has a high fever. He also has gingival bleeding, jaundice, and scleral icterus. On abdominal exam, he has hepatosplenomegaly. He is admitted for supportive care and close monitoring.
Introduction
  • Classification
    • yellow fever virus
      • a positive-stranded, linear RNA virus
      • a flavivirus and arbovirus with icosahedral capsid
      • transmitted by Aedes mosquito
      • reservoir is human or monkey
  • Epidemiology
    • incidence
      • endemic in South America and Africa
    • risk factors
      • exposure to endemic areas
      • mosquito bites
  • Pathogenesis
    • the virus spreads via blood
    • it infects the liver
      • liver cells die via apoptosis
      • coagulopathy occurs due to loss of hepatic synthesis of clotting factors
  • Associated conditions
    • hemorrhagic fever
  • Prevention
    • live-attenuated virus vaccine
      • given at age 9-12 months in endemic areas
      • given 10 days prior to travel to endemic areas
  • Prognosis
    • most patients recover without complications
    • however, in severe cases, mortality rate is up to 60%    
Presentation
  • Symptoms
    • most patients are asymptomatic
    • if symptomatic
      • flu-like prodrome
      • headache
      • myalgias
      • nausea
      • black vomitus
  • Physical exam
    • high fever
    • jaundice
    • scleral icterus
    • hepatomegaly
    • minor hemorrhage
      • epistaxis
      • mucosal bleeding
      • melena
Studies
  • Labs
    • diagnostic
      • reverse transcriptase-polymerase chain reaction
      • serology with enzyme-linked immunosorbent assay
    • transaminitis (AST > ALT)
    • elevated prothrombin and partial thromboplastin times
    • hyperbilirubinemia
  • Guaiac stool testing
    • occult blood
  • Liver biopsy
    • Councilman bodies
      • eosinophilic apoptotic globules
    • typically found on autopsy
  • Making the diagnosis
    • most cases are clinically diagnosed, especially in those who have recently traveled to an endemic area
Differential
  • Dengue fever
    • distinguishing factor
      • may also be hemorrhagic but does not affect the liver
      • will not present with jaundice, scleral icterus, and hepatomegaly
  • Chikungunya 
    • distinguishing factor
      • typically does not present with hemorrhage
Treatment
  • Conservative
    • supportive care
      • indication
        • all patients
      • modalities
        • rehydration
        • close monitoring
        • pain control
Complications
  • Shock
  • Death
  • Prolonged weakness and fatigue
 

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Questions (1)

(M1.MC.17.4754) A 45-year-old male presents to the emergency room complaining of severe nausea and vomiting. He returned from a business trip to Nigeria five days ago. Since then, he has developed progressively worsening fevers, headache, nausea, and vomiting. He has lost his appetite and cannot hold down food or water. He did not receive any vaccinations before traveling. His medical history is notable for alcohol abuse and peptic ulcer disease for which he takes omeprazole regularly. His temperature is 103.0°F (39.4°C), blood pressure is 100/70 mmHg, pulse is 128/min, and respirations are 22/min. Physical examination reveals scleral icterus, hepatomegaly, and tenderness to palpation in the right and left upper quadrants. While in the examination room, he vomits up dark vomitus. The patient is admitted and started on multiple anti-protozoal and anti-bacterial medications. Serology studies are pending; however, the patient dies soon after admission. The virus that likely gave rise to this patient’s condition is part of which of the following families? Tested Concept

QID: 108952
1

Flavivirus

57%

(156/276)

2

Togavirus

12%

(34/276)

3

Calicivirus

7%

(18/276)

4

Bunyavirus

9%

(25/276)

5

Hepevirus

10%

(28/276)

M 1 B

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