Dengue Fever

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A comprehensive topic overview

Introduction

Dengue fever is a self-limiting
Dengue fever is typically spread by the mosquito A e d e s a e g y p t i which is common in the tropics worldwide, especially
1 2
Southeast Asia, Africa, the Paci

Aetiology

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

Risk factors for contracting dengue fever include\:
3
Living or travelling to dengue-endemic areas
Poor public hygiene
High population density

Clinical features

The clinical features of dengue fever di
Febrile phase
The febrile phase usually lasts two to seven days.
History
Typical symptoms of the febrile phase include\:
High-grade fever
Maculopapular rash
Facial
Muscle and joint pains
Severe headache
Retro-orbital pain
Nausea or vomiting
Clinical examinationTypical
Maculopapular rash sparing palms and soles (Figure 1)
Positive tourniquet test\: in
petechiae per 2.5cm.
2
Figure 1. Maculopapular rash of
dengue fever
Critical phase
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.
History
Typical symptoms of the critical phase include\:
Severe abdominal pain
Persistent vomiting
Rapid breathing
Lethargy
Altered consciousness level
Restlessness
Clinical examination
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 re
Signs that indicate severe dengue include\:
Clinical
Periorbital oedema
Hypovolaemic shock
Severe bleeding
Recovery phase
following 48 to 72 hours.
During the recovery phase, the leaked plasma is reabsorbed into the bloodstream. The individual generally improves in the
Clinical examination
Some patients may develop a rash known as “isles of white in a sea of red” which indicates recovery (Figure 2).
3Figure 2. “Isles of white in a sea of red” indicating recovery phase.
Classi
The severity of dengue is classiWHO Dengue Classi (Table 1).
Table 1. The classi
Probable dengue
1. Live in or travel or
travel to dengue-
endemic areas
2. Fever
3. Two of the following
criteria\:
Nausea, vomiting
Rash
Aches and pains
Positive tourniquet
test
Leukopaenia
Any warning sign
Dengue with warning
signs
1. Abdominal pain
2. Persistent vomiting
3. Clinical
accumulation
4. Mucosal bleed
5. Lethargy
6. Restlessness
7. Tender liver
8. Increase in
haematocrit with a rapid
decrease in platelet
count
Severe dengue
1. Severe plasma
leakage\:
Dengue shock
syndrome
Fluid accumulation
with respiratory
distress
2. Severe haemorrhage
3. Severe organ
impairment\:
Liver impairment
Central nervous
system impairment
Cardiac failure

Di

Possible di
3
Malaria
Typhoid fever
HIV seroconversion
Infectious mononucleosis
Measles
Erythema infectiosum
Chikungunya
Zika virus
COVID-19Investigations
Bedside investigations
Relevant bedside investigations in the context of dengue fever include\:
Blood pressure\: hypotension may result from dengue shock syndrome
Laboratory investigations
Relevant laboratory investigations in the context of dengue fever include\:
FBC\: raised haematocrit and low platelet count suggests dengue with warning signs (may also present with neutropenia
and leukopenia)
LFTs\: raised ALT and AST suggests severe dengue with organ involvement
U&Es\: there may be electrolyte imbalance due to persistent vomiting
Coagulation screen\: may reveal prolonged APTT and PT
Imaging
Relevant imaging investigations in the context of dengue fever include\:
Chest X-ray\: to assess for pleural e
Other investigations
Diagnostic tests that may be used to con
3,4
NS1 antigen test\: detected in
IgM antibodies with ELISA\: detected after 5 days of illness and peaks 2 weeks after onset of symptoms
IgG antibodies with ELISA\: detected after 7 days of illness and lasts for life (used to con

Management

Initial management
Most dengue patients do not need hospital admission and there is no speci
However, patients must be evaluated for warning signs and the possibility of developing severe dengue. Key points of
management include\:
Controlling fever with paracetamol
Notifying Public Health England
IV
Escalation of patients with warning signs and severe dengue to a secondary health care facility
Prevention
Some steps that can be taken to prevent dengue fever especially during travel include\:
5
Wearing long-sleeved clothes
Spraying insect repellent
Removing any sources of breeding sites

Complications

Potential complications of dengue fever include\:
3
Dengue haemorrhagic fever
Disseminated intravascular coagulation
Dengue shock syndrome
Severe organ involvement (e.g. cardiac failure, liver impairment)Key points
Dengue fever is a self-limiting
Dengue fever has three phases\: febrile phase, critical phase and recovery phase.
The severity of dengue fever can be divided into non-severe dengue, non-severe dengue with warning signs and
severe dengue.
Laboratory investigations including FBC, LFTs and U&Es as well as diagnostic tests for dengue should be carried out if
dengue is suspected.
Dengue is a self-limiting illness and patients are usually admitted if they develop warning signs or severe dengue.
Complications of developing dengue fever include dengue haemorrhagic fever, dengue shock syndrome, disseminated
intravascular coagulation and organ impairment.

References

Ralston, S. H., Penman, I. D., Strachan, M. W. J., & Hobson, R. (Eds.). Davidson’s principles and practice of medicine (23rd ed.).
Published in 2018. Elsevier Health Sciences.
UpToDate. D e n g u e v i r u s i n f e c t i o n \: C l i n i c a l m a n i f e s t a t i o n s a n d d i a g n o s i s . Patient.info. D e n g u e . Published in 2016. Available from\: [LINK]
World Health Organization. D e n g u e \: g u i d e l i n e s f o r d i a g n o s i s , Available from\: [LINK]
Published in 2021. Available from\: [LINK]
t r e a t m e n t , p r e v e n t i o n a n d c o n t r o l . Published in 2009.
World Health Organization. D e n g u e a n d s e v e r e d e n g u e . Published in 2021. Available from\: [LINK]
Image references
United States Military. D e n g u e r a s h . Licence\: [Public Domain]
Ranjan Premaratna. D e n g u e r e c o v e r y r a s h ( W h i t e i s l a n d s i n r e d s e a ) . Licence\: [CC BY-SA]

Related notes

Chickenpox (VZV)

Reviewer

Clostridioides di
Professor Edmund Ong Liang Chai
COVID-19
Consultant Physician in Infectious Diseases
Human Immunode
Human Papillomavirus (HPV) and Genital Warts

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Contents

Introduction
Aetiology
Risk factors
Clinical features
Di
Investigations
ManagementSource\: geekymedics.com