Dengue fever is an infectious, self-limiting flu-like illness caused by the dengue virus (a type of flavivirus). It is usually spread by the mosquito Aedes aegypti, found in the tropics worldwide, particularly Southeast Asia, Africa, the Pacific and the Americas.1 Less commonly, Aedes albopictus is a source of transmission.2
There are four serotypes of the dengue virus, DEN-1, DEN-2, DEN-3 and DEN-4. People exposed to the virus have lifelong immunity.2 However, if someone with immunity to one serotype is infected with another, they can experience severe dengue.1 The incubation period usually lasts two to seven days, with three phases - the febrile phase, critical phase and recovery phase.1
Factors that increases one's chances of contracting dengue fever include living or travelling to dengue-endemic areas, poor public hygiene, and high population density.3
The symptoms of dengue fever vary according to the phase of the disease.
The febrile phase typically lasts two to seven days.
Common symptoms during the febrile phase include: high-grade fever, maculopapular rash, facial flushing, muscle and joint pains, severe headache, retro-orbital pain and nausea or vomiting.
Typical findings on clinical examination include: maculopapular rash (not present on palms and soles) and a positive tourniquet test (>20 petechiae per 2.5cm when inflated blood pressure cuff is applied for five minutes).2
The critical phase usually begins after the third day of fever and lasts for 24 to 48 hours. There is an increase in capillary permeability and a drop in body temperature.
Dengue is classified using the World Health Organization Dengue Classification 2009 (Table 1). It consists of three categories: probable dengue, dengue with warning signs, and severe dengue.
Common symptoms of the critical phase include:
Signs of non-severe dengue include:
Important signs to not miss out which may indicate dengue with warning signs include:
Signs that indicate severe dengue include:
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.
The severity of dengue is classified using the WHO Dengue Classification 2009 (Table 1). It consists of three categories: probable dengue, dengue with warning signs, and severe dengue.
Table 1. The classification of severity for dengue fever.
Dengue with warning signs
1. Live in or travel or travel to dengue-endemic areas
3. Two of the following criteria:
1. Abdominal pain
2. Persistent vomiting
3. Clinical fluid accumulation
4. Mucosal bleed
7. Tender liver
8. Increase in haematocrit with a rapid decrease in platelet count
1. Severe plasma leakage:
2. Severe haemorrhage
Possible types of severe organ impairment associated with dengue fever include:
In the context of suspected dengue fever, the possible differential diagnoses include:
Relevant bedside investigations in the context of dengue fever include:
Relevant laboratory investigations in the context of dengue fever include:
Relevant imaging investigations in the context of dengue fever include:
Diagnostic tests that may be used to confirm dengue fever include:
Most dengue patients do not need hospital admission and there is no specific treatment for dengue fever. However, patients must be evaluated for warning signs and the possibility of developing severe dengue. Key points of management include:
Some steps that can be taken to prevent dengue fever especially during travel include:
Potential complications of dengue fever include:
Laboratory investigations such as Full Blood Count (FBC), Liver Function Tests (LFTs) and Urine and Electrolytes (U&Es) as well as diagnostic tests should be carried out if dengue is suspected. Dengue is a self-limiting illness and patients are usually admitted if they show warning signs or severe dengue. Complications of developing dengue fever include dengue haemorrhagic fever, dengue shock syndrome, disseminated intravascular coagulation and organ impairment.
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