Dengue

Snapshot

A 44-year-old woman presents to the emergency room for high fever, chills, headache, and nose bleed. She had recently traveled to Taiwan for 3 days, where she enjoyed both city-life and tropical tourism. She had been bit by mosquitoes throughout her trip. Severals days after returning to the USA, she developed a high fever, joint and muscle pain, and nose bleeds. On physical exam, there is a confluent erythematous macular rash on her trunk. There is also some gingival bleeding. She is admitted for monitoring and supportive care.

Introduction

Classification
- dengue virus
  - an enveloped, positive-sense, single-stranded RNA flavivirus
- transmission
  - Aedes mosquitoes
Epidemiology
- incidence
  - tropical and subtropical areas of the world
- risk factors
  - prior infection with dengue virus predisposes patients to severe dengue hemorrhagic fever
Pathogenesis
- virus replicates in and destroys the bone marrow
- plasma leakage is caused by increased capillary permeability
Associated conditions
- dengue hemorrhagic fever or dengue shock syndrome
Prognosis
- symptoms occur after 4-10 days
- if untreated, mortality rates can be 20%
if treated, mortality rate is 2-5% in severe cases

Presentation

Symptoms
- headache
- myalgais and arthralgias
- altered sense of taste
Physical exam
- high fever
- blanching confluent erythematous maculopapular rash
- lymphadenopathy
- may have pleural effusions
- minor hemorrhage
  - petechiae
  - bleeding mucosa
  - epistaxis
- in severe cases, plasma leakage occurs
  - bleeding from sites of trauma
  - gastrointestinal bleeding
  - severe abdominal pain
  - blood vomiting
- positive tourniquet test
petechiae observed below the cuff after a tourniquet (commonly an inflated blood pressure cuff) is left on for 5 minutes

Studies

Differential

Yellow fever
- distinguishing factor
  - may also be hemorrhagic but often affects the liver as well and manifests as jaundice, scleral icterus, and hepatomegaly
Zika virus infection
- distinguishing factors
  - may also present with prodrome and rash, but typically does not have any hemorrhage
  - pregnant patients may give birth to infants with microcephaly and intracranial calcifications
Chikungunya
- distinguishing factor
may also present with flu-like symptoms, joint pain, and rash, but typically does not have any hemorrhage

Treatment

Management approach
- the disease is typically self-limited and mainstay for treatment is supportive care
Conservative
- supportive care
  - indication
    - all patients
  - modalities
    - rehydration
    - close monitoring
pain control

Complications