Dengue Signs and Symptoms

Etiology

  • Incubation period
    • Extrinsic (within mosquito vector): 8-10 days
    • Intrinsic (within human host): 3-14 days (average of 4-7 days)
  • Transmission to humans is usually through the bite of an infected Aedes mosquito
    • Primarily transmitted by female Aedes aegypti, a tropical and subtropical species
    • Other outbreaks were secondary to A albopictus, A polynesiensis, A scutellaris
    • Humans are the main host of the virus
  • 4 serotypes: DENV-1, DENV-2, DENV-3, DENV-4
    • Each serotype provides specific lifetime protective immunity against reinfection of the same serotype, but only temporary (within 2-3 months of the primary infection) and partial protection against the other serotypes
  • The fifth serotype, DENV-5, is a new variant that follows the sylvatic cycle (transmission of dengue virus to non-human primates) while the other 4 serotypes are transmitted between humans
  • After 4-10 days of incubation period, illness begins immediately

Signs and Symptoms

Phases of Dengue Infection
Febrile Phase

  • Patient suddenly develops high-grade fever that commonly lasts for 2-7 days and is associated with facial flushing, skin redness, generalized arthralgia, myalgia, headache, anorexia, nausea, vomiting
    • May also be accompanied by sore throat, injected pharynx, conjunctival injection, mucosal/gastrointestinal bleeding
    • Likelihood of dengue infection is increased by a positive torniquet test and progressive decrease in total WBC count
    • Progression to critical phase should be recognized promptly by monitoring for warning signs and other clinical parameters

Critical Phase

  • Occurs on days 3-7 of illness and usually lasts for 1-2 days
  • Patient’s temperature lowers to ≤37.5-38°C and may have increase in capillary permeability concurrent with increase in hematocrit level
  • Patient may develop pleural effusion, ascites, shock, organ impairment, metabolic acidosis, disseminated intravascular coagulation which may lead to severe hemorrhage
    • Depends on the degree of plasma leakage and the volume of fluid therapy
  • Other patients may proceed with this phase even without defervescence
    • Changes in the full blood count may be the only guide to determine the onset of plasma leakage

Recovery Phase

  • 2-3 days after critical phase has been successfully surpassed
  • Patients may present with respiratory distress due to massive pleural effusion and ascites if excessive IV fluids were given