Dengue

Background

World map highlighting areas of dengue risk.

• A viral infection transmitted though Aedes mosquitos typically in urban areas, especially during rainy seasons in tropical/subtropic regions (Asia, Africa, Central America, Caribbean)
• Most infections are asymptomatic or produce only mild illness, but the virus occasionally causes more severe cases up to death (i.e., "severe dengue")
  • Severe dengue (which includes "dengue shock syndrome") is rare in travelers, as it is cause by a second infection of a different Dengue serotype (so patients must have had two exposures to be at risk)

Clinical Features

• Incubation 3-7 days
• Febrile phase:
  • High fever + 'Breakbone' + GI symptoms + rash + possible exposure
  • +/- Faget sign
  • Lasts 3-7 days, majority recover
• Critical Phase:
  • Minority of patients, generally pediatric and elderly
  • Around time of defervescence
  • Vascular leak, hypoproteinemia, hemoconcentration, pleural effusion, ascites
  • Narrowed pulse pressure, persistent vomiting, RUQ tenderness, lethargy and restlessness are signs of impending collapse
  • Mucosal and skin bleeding
• "Severe Dengue," any of the following:
  • Shock from plasma leakage
  • Hemorrhage
  • Respiratory distress

Differential Diagnosis

Fever in traveler

• Normal causes of acute fever!
• Malaria
• Dengue
• Leptospirosis
• Typhoid fever
• Typhus
• Viral hemorrhagic fevers
  • Ebola virus disease
  • Marburg virus disease
  • Lassa fever
  • Crimean-Congo hemorrhagic fever
• Chikungunya
• Yellow fever
• Rift valley fever
• Q fever
• Amebiasis
• Zika virus

Evaluation

Work-up

Example of positive tourniquet test on the right

• Labs:
  • CBC: Leukopenia, thrombocytopenia, and hemoconcentration
  • CMP: LFTs elevated
  • DIC labs should be sent
  • Diagnose by 4x increase in acute/ convalescent titres - unlikely to be resulted in ED
• Tourniquet Test - Tests capillary fragility
  • Sensitivity of 52% and specificity of 82.4%
  • A positive tourniquet test combined with lekuopenia increases sensitivity to 94%
  • Inflate cuff to pressure between SBP & DBP, and leave for 5 min
  • (+) Test = 10-20 petechiae per square inch

• Definitive testing
  • Reverse transcription polymerase chain reaction [RT-PCR] and IgM antibody tests, or non-structural protein 1 [NS1] antigen tests and IgM antibody tests
  • For public health purposes, these tests may be ordered regardless of time since symptom onset

Diagnosis

• Clinical diagnosis

Management

• Supportive Care
  • Acetaminophen for pain/fever
    • DO NOT use aspirin due to hemorrhagic nature
• IVFs
• Blood Transfusion - consider in hemorrhagic shock

Disposition

• Home - Well hydrated and non-toxic appearing
• Admit - High-risk patients (ie pregnant, elderly, children, chronic disease)
  • ICU - patients with shock and end-organ damage

Prevention

• Vaccine available for the prevention of dengue virus and associated severe sequelae, Dengvaxia.
• Only recommended for individuals 9-45 years old who have been infected once before with the virus.
• If patient has confirmed or likely dengue virus infection and they live and/or work in an endemic area, have them follow up with PCP for vaccination.

See Also

• Travel Medicine
• Neglected Tropical Diseases