Dengue

Question 1

Clinical presentation of Dengue

Answer 1

Asymptomatic
* Up to 50% of all dengue infected individuals

Fever with mild / non-specific symptoms
* Mimics other benign acute febrile illnesses
* Typically young children or those experiencing their first infection,
and they recover fully without need for hospital care
* Without diagnostic testing, the diagnosis of dengue would be missed

Symptomatic Dengue

Question 2

Describe Clinical phases of Dengue:
* Febrile phase

Answer 2

• typically develop high-grade fever suddenly
• fever usually lasts 2–7 days
• often accompanied by facial flushing, skin erythema, generalized body ache, myalgia, arthralgia and headache
• anorexia, nausea and vomiting are common
• some patients may have sore throat, injected pharynx and conjunctival injection
• can be difficult to distinguish dengue clinically from other infections
• clinical features are indistinguishable between severe and non-severe
  dengue cases - monitor for warning signs (progression to critical phase)
• mild haemorrhagic manifestations like petechiae and mucosal membrane
  bleeding (e.g. nose and gums) may be seen
• positive tourniquet test in this phase increases the probability of dengue
• FBC – drop in total white cell count?

Question 3

List the clinical phases of dengue (3)

Answer 3

• Febrile phase
• Critical phase (which may lead to Severe Dengue)
• Recovery phase

Question 4

Describe Clinical phases of Dengue:
* Critical phase (which may lead to Severe Dengue)
P___ P___

Answer 4

critical

Severe dengue:
Importance of pulse pressure:
The patient is considered to have shock if :
* the pulse pressure (i.e. systolic BP - diastolic BP) is ≤
20 mm Hg in children
or he/she has signs of :
* of poor capillary perfusion (cold extremities, delayed
capillary refill, or rapid pulse rate).
* In adults, the pulse pressure of ≤ 20 mm Hg may indicate a more severe shock.
Profound shock with thrombocytopenia, hypoxia and acidosis–> multiple organ failure
–> advanced disseminated intravascular coagulation (DIC)
massive bleeding

• Pulse pressure ≤ 20 mmHg (sys-dia) is SHOCK

Question 5

Clinical description of Dengue

Answer 5

1997 (traditional WHO classification) case definitions:
* Dengue fever
* Dengue haemorraghic fever (DHF)
* Dengue shock syndrome (DSS)
HOWEVER
Difficulties in applying the criteria for DHF in the clinical situation, together with the increase in clinically severe dengue cases which did not fulfil the strict criteria of DHF, led to reclassification.

Question 6

Diagnostic tests for Dengue

Answer 6

• PCR to look for Dengue virus (send blood in FBC blood tube)
• Serum for POCT (Dengue Duo test for IgM / IgG and
  NS1 antigen)
• Serum for Dengue antibody testing