Dengue Fever Flashcards
(20 cards)
What virus causes dengue fever?
Flavivirus
What is the vector for dengue fever
Aedes mosquito
What type of virus is flavivirus
Single-stranded RNA
Risk factors for dengue
High population
Poor hygiene
Travel to endemic countries (Africa, SEA, west America, Pacifics)
Risk factors for severe dengue
Children <15y/o
Repeated dengue infection
Specific viral genotypes
Malnourished children
What are the serotypes for dengue? Which types are associated with severe disease?
DEN-1 to DEN-4
DEN-2 and DEN-3 are associated with severe disease
What is the incubation period for dengue?
4-10 days
Which cells do they proliferate in?
B cells, macrophages, monocytes, mast cells, dendritic cells and endothelial cells
What are the signs of dengue fever (without warning)?
Fever with two of the following:
- Nausea/vomiting
- Rash
- Aches and pains
- Positive tourniquet test
- Leukopenia
What are the warning signs of dengue?
Abdominal pain
Hepatomegaly >2cm
Persistent vomiting
Clinical fluid accumulation
Lethargy
Restlessness
Increased haematocrit with reducing platelets
What is the clinical presentation of dengue?
Intermittent high pyrexias (3-7 days)
Arthralgia
Rash - maculopapular rash, may develop into petechiae
Bleeding manifestations - bleeding gums, epistaxis, GI bleeds
Symptoms of severe dengue include:
Pulmonary and facial oedema
Ascites
Pleural effusions
Meningism
Worsening or profuse haemorrhage
How does dengue cause bleeding?
Increased vascular permeability due to capillary leakage causing plasma leakage into tissues > cytokine response and suppression of T-cell response
Non-specific features of dengue
Headache
N+V
Lymphadenopathy
Generalised myalgia
Backache
Ocular manifestations - retro-orbital pain, conjuctival infection and conjuctivitis
What happens to the platelets and leucocytes in dengue? What biochemical marker is associated with clinical deterioration?
Thrombocytopenia (low platelets)
Leucopenia (low WCC)
Haematocrit is a marker of clinical deterioration - high haematocrit indicates deterioration of clinical condition
Investigations for dengue?
Viral isolation from serum (needs to be collected in viraemic phase, before day 5)
PCR
Antibody detection using ELISA IgM and IgG
Tourniquet test
What is the management of dengue?
Conservative treatment with supportive therapy if needed
May required ITU / HDU if severe dengue
Observing FBC (platelets, WCC, haematocrit)
Why should aspirin be avoided, especially in children
Increases bleeding risk
Reye’s syndrome in children
What is Reye’s syndrome?
Acute non-inflammatory encephalitis with fatty liver failure
Complications of dengue
Hepatic failure
Encephalopathy
Myocarditis
DIC
Septicaemia
Haemorrhage + shock
