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Overview
Dengue fever is an acute febrile disease caused by the dengue virus. There are four different circulating serotypes of dengue virus (DENV 1 to 4) circulating in the world, including Singapore. Hence, individuals can be infected with dengue up to four times.
Pathogen(s)
Dengue virus, a member of the Flaviviridae family. There are four serotypes (DENV 1, 2, 3, and 4).
Transmission
Transmitted via the bite of an infective Aedes aegypti and Aedes albopictus mosquitoes.
Incubation period: Typically 4 to 7 days; range is 3 to 14 days.
Infectious period: Infectious to mosquitoes from 2 days before, to 5 days after illness onset (when the patient is viraemic).
Clinical features
Dengue fever:
Acute onset of fever which lasts for 2 to 7 days with 2 or more of the following:
Headache, backache, myalgia
Rash: maculopapular or flush; petechial with islands of sparing
Retro-orbital pain
Bleeding
Leucopenia
Thrombocytopenia may also occur and usually worsens when fever resolves
Dengue haemorrhagic fever (DHF)
For a diagnosis of DHF, a case must fulfil all four of the following criteria:
Fever
Bleeding manifestations (e.g. petechiae, ecchymosis, epistaxis, gum bleeding, haematemesis, or melena)
Thrombocytopenia (< 100 X 109/L)
Evidence of increased capillary permeability
Haematocrit increased by >20% above baseline
Pleural effusion
Hypoalbuminaemia
Dengue shock syndrome (DSS)
For a diagnosis of DSS, all four criteria for DHF must be met, in addition to hypotension, narrowed pulse pressure (< 20 mm Hg) and impaired organ perfusion.
Risk factors
Risk factors include:
Living in or travelling to Dengue-affected areas
Diagnosis
There are combination tests such as dengue NS1, IgM and IgG available for laboratory diagnosis of dengue.
NS1 antigen assay (rapid test): Positive for dengue NS1 protein within the first week of onset
PCR: Positive for dengue virus within 5 days of onset
Serology: Positive dengue IgM on acute serum sample A high-titre IgG antibody may also be indicative of dengue, particularly secondary infection. IgM antibodies appear on approximately the fifth day of illness and last for 2 months. A 4-fold rise in titres of a pair of acute and convalescent sera is confirmatory.
Treatment and management
There is currently no specific treatment for dengue fever. Treatment is mainly supportive.
Symptomatic treatment includes paracetamol for fever and/or pain. Paracetamol should be used with caution in patients with liver disease or transaminitis
If necessary, low dose tramadol may be used for pain in those situation, and tepid sponging for fever.
Non-steroidal anti-inflammatory drugs should be avoided as they can increase the risk of bleeding.
Patient should be advised to stay well hydrated.
For those with severe dengue, hospitalisation is required.
Precaution, prevention, and control
Standard precautions apply in healthcare settings.
The manufacturer for Dengvaxia, which is currently the only licensed dengue vaccine in Singapore, has indicated that the vaccine will be discontinued due to low global demand for this product. This decision is not driven by quality, safety or efficacy concerns. As of May 2025, Dengvaxia is only available in Singapore on a first-come-first-serve basis for individuals who have already initiated the 3-dose series.
Dengvaxia is administered in a 3-dose schedule 6 months apart (at month 0, 6, and 12). To ensure completion of the full series, individuals should have received their first dose no later than May 2025. Please contact Sanofi for more information on stock availability and corresponding expiration date for individuals who need to complete the remaining dose(s) in the series.
Vector control remains the mainstay in reducing the spread of mosquito-borne diseases. Individuals can also take precautions against mosquito bites, such as:
Staying in rooms which are well-screened from insects from the exterior.
Wearing long, protective clothing that covers most of one’s body.
Using effective insect repellent (e.g. those containing DEET, Picaridin or IR3535 as the active ingredient) and re-applying ever four to six hours on exposed skin.
Notification
Who should notify:
Medical practitioners
Laboratories
When to notify:
On clinical suspicion or laboratory confirmation
How to notify:
Please refer to the Infectious Disease Notification for more information.
Notification timeline:
As soon as possible. No later than 24 hours from the time of diagnosis.
Resources
Please refer to the Weekly Infectious Diseases Bulletin for the numbers of confirmed dengue cases in Singapore.
National Environment Agency (NEA) website on dengue cases and clusters.