Treatment Guideline Chart

Dengue infection is caused by the dengue virus that belongs to the family Flaviviridae. It is generally self-limiting and rarely fatal.
There are 4 serotypes (DEN-1, DEN-2, DEN-3, DEN-4). Infection with dengue serotype confers lifetime protective immunity to that specific serotype; cross-protection for other serotypes is only short-term.
It is transmitted to humans through the bites of infected Aedes mosquitoes. It is primarily transmitted by female Aedes aegypti, a tropical and subtropical species. Humans and monkeys are the amplifying hosts after the mosquito bite.
After 4-10 days of incubation period, illness begins immediately.
The acute phase of illness lasts for 3-7 days, but the convalescent phase may be prolonged for a week and may be associated with weakness and depression especially in adults.

Dengue Signs and Symptoms


  • Globally, estimated dengue infections climb up to 390 million per year, with 96 million symptomatic individuals, with 70% of the burden coming from Asia
  • An 8-fold increase has been reported to the World Health Organization (WHO) in the past 2 decades
  • Data on dengue cases decreased in 2020-2021 but inconclusive due to the coronavirus disease 2019 (COVID-19) 
  • In Singapore, 35,315 cases were reported in 2020, and >12,000 cases have been reported as of June 2022
  • An increase of approximately 300 cases compared to the same period in 2021 has been noted by the National Dengue Control Programme (NDCP) of Cambodia, with >1,200 confirmed cases reported within the first 5 months of 2022
  • Reported mortality rates from 2000 to 2015 increased from 960 to 4032, with a decline in the total cases in 2020-2021


  • 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
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