Dengue Fever

Question 1

What virus causes dengue fever?

Answer 1

Flavivirus

Question 2

What is the vector for dengue fever

Answer 2

Aedes mosquito

Question 3

What type of virus is flavivirus

Answer 3

Single-stranded RNA

Question 4

Risk factors for dengue

Answer 4

High population
Poor hygiene
Travel to endemic countries (Africa, SEA, west America, Pacifics)

Question 5

Risk factors for severe dengue

Answer 5

Children <15y/o
Repeated dengue infection
Specific viral genotypes
Malnourished children

Question 6

What are the serotypes for dengue? Which types are associated with severe disease?

Answer 6

DEN-1 to DEN-4
DEN-2 and DEN-3 are associated with severe disease

Question 7

What is the incubation period for dengue?

Answer 7

4-10 days

Question 8

Which cells do they proliferate in?

Answer 8

B cells, macrophages, monocytes, mast cells, dendritic cells and endothelial cells

Question 9

What are the signs of dengue fever (without warning)?

Answer 9

Fever with two of the following:
- Nausea/vomiting
- Rash
- Aches and pains
- Positive tourniquet test
- Leukopenia

Question 10

What are the warning signs of dengue?

Answer 10

Abdominal pain
Hepatomegaly >2cm
Persistent vomiting
Clinical fluid accumulation
Lethargy
Restlessness
Increased haematocrit with reducing platelets

Question 11

What is the clinical presentation of dengue?

Answer 11

Intermittent high pyrexias (3-7 days)
Arthralgia
Rash - maculopapular rash, may develop into petechiae
Bleeding manifestations - bleeding gums, epistaxis, GI bleeds

Question 12

Symptoms of severe dengue include:

Answer 12

Pulmonary and facial oedema
Ascites
Pleural effusions
Meningism
Worsening or profuse haemorrhage

Question 13

How does dengue cause bleeding?

Answer 13

Increased vascular permeability due to capillary leakage causing plasma leakage into tissues > cytokine response and suppression of T-cell response

Question 14

Non-specific features of dengue

Answer 14

Headache
N+V
Lymphadenopathy
Generalised myalgia
Backache
Ocular manifestations - retro-orbital pain, conjuctival infection and conjuctivitis

Question 15

What happens to the platelets and leucocytes in dengue? What biochemical marker is associated with clinical deterioration?

Answer 15

Thrombocytopenia (low platelets)
Leucopenia (low WCC)
Haematocrit is a marker of clinical deterioration - high haematocrit indicates deterioration of clinical condition

Question 16

Investigations for dengue?

Answer 16

Viral isolation from serum (needs to be collected in viraemic phase, before day 5)
PCR
Antibody detection using ELISA IgM and IgG
Tourniquet test

Question 17

What is the management of dengue?

Answer 17

Conservative treatment with supportive therapy if needed
May required ITU / HDU if severe dengue
Observing FBC (platelets, WCC, haematocrit)

Question 18

Why should aspirin be avoided, especially in children

Answer 18

Increases bleeding risk
Reye’s syndrome in children

Question 19

What is Reye’s syndrome?

Answer 19

Acute non-inflammatory encephalitis with fatty liver failure

Question 20

Complications of dengue

Answer 20

Hepatic failure
Encephalopathy
Myocarditis
DIC
Septicaemia
Haemorrhage + shock