Dengue fever is a self-limiting flu-like illness that is caused by the dengue virus (a type of flavivirus).
Dengue fever is typically spread by the mosquito Aedes aegypti which is common in the tropics worldwide, especially Southeast Asia, Africa, the Pacific and the Americas.1 It is less commonly spread by Aedes albopictus.2
There are four serotypes of the dengue virus: DEN-1, DEN-2, DEN-3 and DEN-4.
Those who are infected by the dengue virus develop life-long immunity.2 However, individuals with previous immunity to one serotype infected with another serotype can develop severe dengue.1
The incubation period of dengue fever is usually two to seven days. There are three phases of dengue fever: febrile phase, critical phase and recovery phase.1
Risk factors for contracting dengue fever include:3
Living or travelling to dengue-endemic areas
Poor public hygiene
High population density
The clinical features of dengue fever differ according to the phase of the disease.
The febrile phase usually lasts two to seven days.
Typical symptoms of the febrile phase include:
Muscle and joint pains
Nausea or vomiting
Typical findings on clinical examination include:
Maculopapular rash sparing palms and soles (Figure 1)
Positive tourniquet test: inflate blood pressure cuff on upper arm for five minutes; a positive test is when there is >20 petechiae per 2.5cm.2
The critical phase usually happens after the third day of fever and lasts for 24 to 48 hours. There is an increase in capillary permeability with a drop in body temperature.
Typical symptoms of the critical phase include:
Severe abdominal pain
Altered consciousness level
Signs of non-severe dengue include:
Maculopapular rash sparing palms and soles
Positive tourniquet test
Important signs to not miss out which may indicate dengue with warning signs include:
Haemorrhagic manifestations: petechiae, mucosal membrane bleeding and menorrhagia
Enlarged and tender liver
Evidence of shock: prolonged capillary refill time
Signs that indicate severe dengue include:
Clinical fluid accumulation: pleural effusion and ascites
During the recovery phase, the leaked plasma is reabsorbed into the bloodstream. The individual generally improves in the following 48 to 72 hours.
Some patients may develop a rash known as “isles of white in a sea of red” which indicates recovery (Figure 2).3