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ALL / Infectious Diseases
Dengue fever
Dengue fever
Dengue fever is a viral infection that can progress to viral haemorrhagic fever (other examples include yellow fever, Lassa fever, Ebola).Aetiology
- dengue virus is a RNA virus of the genus Flavivirus
- transmitted by the Aedes aegypti mosquito
- incubation period of 7 days
Clinical features
Patients with dengue fever can be classified as follows:
- dengue fever:
- without warning signs
- with warning signs
- severe dengue (dengue haemorrhagic fever)
Dengue fever
- fever
- headache (often retro-orbital)
- myalgia, bone pain and arthralgia ('break-bone fever')
- pleuritic pain
- facial flushing (dengue)
- maculopapular rash
- haemorrhagic manifestations e.g. positive tourniquet test, petechiae, purpura/ecchymosis, epistaxis
- 'warning signs' include:
- abdominal pain
- hepatomegaly
- persistent vomiting
- clinical fluid accumulation (ascites, pleural effusion)
Severe dengue (dengue haemorrhagic fever)
- this is a form of disseminated intravascular coagulation (DIC) resulting in:
- thrombocytopenia
- spontaneous bleeding
- around 20-30% of these patients go on to develop dengue shock syndrome (DSS)
Investigations
- typically blood results
- leukopenia, thrombocytopenia, raised aminotransferases
- diagnostic tests: early phase (first 0-5 days of illness)
- NS1 antigen test (quick, reliable; positive confirms infection)
- nucleic acid amplification tests for viral RNA (gold standard for confirming infection and identifying the serotype)
- diagnostic tests: later phase (≥5 days): detect immune response
- IgM/IgG antibodies
Treatment
- entirely symptomatic e.g. fluid resuscitation, blood transfusion etc
- no antivirals are currently available
+PassMedicine Notes
Dengue fever is a viral infection that can progress to viral haemorrhagic fever (other examples include yellow fever, Lassa fever, Ebola).
Aetiology- dengue virus is a RNA virus of the genus Flavivirus
- transmitted by the Aedes aegypti mosquito
- incubation period of 7 days
Clinical features
Patients with dengue fever can be classified as follows:- dengue fever:
- without warning signs
- with warning signs
- severe dengue (dengue haemorrhagic fever)
- fever
- headache (often retro-orbital)
- myalgia, bone pain and arthralgia ('break-bone fever')
- pleuritic pain
- facial flushing (dengue)
- maculopapular rash
- haemorrhagic manifestations e.g. positive tourniquet test, petechiae, purpura/ecchymosis, epistaxis
- 'warning signs' include:
- abdominal pain
- hepatomegaly
- persistent vomiting
- clinical fluid accumulation (ascites, pleural effusion)
- this is a form of disseminated intravascular coagulation (DIC) resulting in:
- thrombocytopenia
- spontaneous bleeding
- around 20-30% of these patients go on to develop dengue shock syndrome (DSS)
- typically blood results
- leukopenia, thrombocytopenia, raised aminotransferases
- diagnostic tests: early phase (first 0-5 days of illness)
- NS1 antigen test (quick, reliable; positive confirms infection)
- nucleic acid amplification tests for viral RNA (gold standard for confirming infection and identifying the serotype)
- diagnostic tests: later phase (≥5 days): detect immune response
- IgM/IgG antibodies
- entirely symptomatic e.g. fluid resuscitation, blood transfusion etc
- no antivirals are currently available