Cause:

• Dengue fever is caused by the dengue virus (DENV), a mosquito-borne flavivirus with four distinct serotypes (DENV-1 to DENV-4). Transmission occurs primarily through the bite of infected Aedes aegypti and Aedes albopictus mosquitoes. Rationale: The virus is endemic in tropical and subtropical regions, with outbreaks often linked to urbanization and poor sanitation.

• Diagnosis:
  • Clinical Criteria:
    • Sudden onset of high fever (40°C/104°F), severe headache, retro-orbital pain, myalgia, arthralgia, and a characteristic rash (maculopapular or petechial).
    • Warning signs (for severe dengue):
      • Persistent vomiting, severe abdominal pain, mucosal bleeding, lethargy, hepatomegaly, and a rapid rise in hematocrit with a drop in platelet count.
  • Laboratory Tests:
    • Complete blood count (CBC): Thrombocytopenia (<100,000/μL) and hemoconcentration (increased hematocrit).
    • Liver function tests (LFTs): Elevated transaminases.
    • Serology: NS1 antigen (for acute infection) or IgM/IgG antibodies (for past infection).
    • PCR: For viral RNA detection in early infection.
  • Imaging: Ultrasound for hepatomegaly or pleural effusion in severe cases.

• Treatment:
  • Supportive Care:
    • Hydration (oral or IV fluids) to prevent dehydration.
    • Paracetamol (avoid NSAIDs like aspirin/ibuprofen due to bleeding risk).
    • Monitor for warning signs (e.g., persistent vomiting, bleeding) requiring hospitalization.
  • Severe Dengue (Dengue Hemorrhagic Fever/Dengue Shock Syndrome):
    • IV fluids (crystalloid/colloid) to correct shock.
    • Blood transfusion (platelets or whole blood) if severe bleeding or thrombocytopenia (<20,000/μL).
    • Close monitoring for organ failure (e.g., liver, kidney).

Key Notes:

• No specific antiviral therapy exists; treatment focuses on symptom management and preventing complications.
• Prevention: Mosquito control (eliminating breeding sites) and vaccination (Dengvaxia, for seropositive individuals in endemic areas).

Would you like details on any specific aspect, such as risk factors or complications?