The various serotypes of the dengue virus are transmitted to humans through the bites of infected Aedes mosquitoes, principally Aedes aegypti. Humans are the main amplifying host of the virus. Dengue virus crculating in the blood of viraemic humans is ingested by female mosquitoes during feeding.
The virus then infects the mosquito mid-gut and subsequently spreads systemically over a period of 8-12 days Dengue infected patients are either asymptomatic or symptomatic. Symptomatic patients have one of three clinical presentations: Undifferentiated fever/ Viral syndrome Dengue fever with or without hemorrhage Dengue hemorrhagic fever or Dengue shock Syndrome
Dengue fever Clinical Features:
Incubation period: 4-5 days
Prodrome phase: It may present with maliase and headache.
Acute onset: Fever with severe generalised pains( so called break bone fever), retro bulbar pain associated with eye movement, lacrimation, conjuctival redness, nausea, vomiling , anorexia.
Baphasic fever (Saddle hack fever); initial phase 3-7 days, remission for few hours to 2 days second pahse, 1-2 days.
Biphasic skin rashes: Initially flushing faint macular rash first 24-48 hours then maculopapular scarlet morbilliform rash from days 3-5 on torso, spreading from extremities to trunk and sparing palms and soles.
Dengue fever signs and symptoms:
The presence of one or more these signs indicates the need for immediate medical evaluation. When no plasma leakage some common symptoms seen are
- Abdominal pain or tenderness
- Persistent vomiting
- Clinical fluid accumulation
- Mucosal bleed
- Lethargy, restlessness
- Liver enlargement >2 cm
- Increase in HCT concurrent with rapid decrease in platelet count
Criteria for severe dengue:
Severe plasma leakage Shock (DSS);
Fluid accumulation with respiratory distress;
Severe bleeding as evaluated by clinician; Severe organ involvement Liver: AST or ALT >=1000 CNS:
Impaired consciousness Heart and other organs;
- Dengue shock syndrome
- Bone marrow suppression
|Article written by Bishal Singh from Siraha Nepal|
Dengue fever diagnosis:
Clinical and laboratory tests for dengue fever are:
Laboratory tests: Blood : CBC: Thrombocytopenia and leucopenia, – ESR: Usually normal Liver function tests: Increases liver enzymes – Serological tests: IgG antibody titers Isolation of virus RNA by PCR
Dengue fever treatment:
No specific treatment for Dengue fever But we can treat it by proper supply of fluid and electrolytes management. NASAIDs ,Aspirin is contraindicated due to increased risk of bleeding.
Patients should eat proper nutritional food. We should use of impregnated nets during sleep. Use of topical insect repellent is necessary. Destroy breeding sites of mosquitoes.