Dengue fever

Disease Description (Causes and Symptoms)

• Cause: Occurs when mosquitoes of the genus Aedes (such as the Aedes mosquito) carrying the dengue virus bite humans and transmit the virus. The mosquitoes that transmit it are active mainly during the daytime in tropical and subtropical regions.
• Pathophysiology: Vascular permeability increases due to vascular endothelial dysfunction and an inflammatory response caused by viral infection, and thrombocytopenia and coagulation abnormalities may occur. In the event of a previous infection, the risk of developing severe forms (dengue hemorrhagic fever or dengue shock) increases through antibody-dependent enhancement (the mechanism of severe disease caused by secondary infection).
• Main symptoms: After an incubation period of 3–14 days (usually 4–7 days), symptoms include high fever, severe headache, muscle and joint pain (myalgia), rash, loss of appetite, and nausea/vomiting. In some cases, petechiae, gum bleeding, and epistaxis may occur; as the disease worsens, it may progress to dengue hemorrhagic fever or dengue shock syndrome, which cause fluid leakage and hypotension.

Treatment Methods

• General principles: No specific antiviral drug has currently been established as a standard treatment, so treatment is primarily supportive care.
• Acute-phase management:
  • Prevent and correct dehydration and reduced blood volume through adequate fluid replacement (oral fluids or intravenous fluids when necessary).
  • Fever reduction: Acetaminophen (such as Tylenol) is recommended. Aspirin, ibuprofen, and other nonsteroidal anti-inflammatory drugs (NSAIDs) are contraindicated because they increase the risk of bleeding.
  • Oxygen therapy and, when necessary, intensive care (maintaining blood pressure and correcting blood components and electrolytes).
  • In cases of severe bleeding or hemodynamic instability, appropriate transfusion (including plasma and platelets) and intensive treatment.
• Hospitalization criteria: Persistent vomiting, severe abdominal pain, persistent bleeding, hypotension or signs of shock, or rapidly progressing thrombocytopenia/hemoconcentration (increased hematocrit), among others.
• Lifestyle management and precautions:
  • Get sufficient rest and drink plenty of fluids (oral electrolyte solutions are recommended).
  • Use acetaminophen as an antipyretic, and consider stopping NSAIDs, anticoagulants, and antiplatelet drugs (e.g., aspirin).
  • If symptoms worsen (severe abdominal pain, persistent vomiting, bloody stool or hematuria, persistent bleeding, dizziness or decreased consciousness, etc.), visit the emergency department immediately.
• Complication management: If hemorrhagic complications, hemodynamic instability, or multiorgan failure develops, intensive care and coordination with relevant specialists are required.

Outpatient Visit Checklist (Including Preparation, Items to Confirm, and Sample Questions)

• Recommended items to bring:
  • List of medications currently being taken (including prescription drugs, over-the-counter medicines, and supplements)
  • Past medical history (particularly any previous dengue infection, blood-clotting disorders, cardiovascular disease, etc.)
  • Recent records of temperature and symptom changes (date fever began, presence of rash, number of vomiting episodes, etc.)
  • Recent test results (if available, including CBC, electrolytes, liver function tests, etc.)
• Items to confirm before the visit:
  • Timing of symptom onset (based on the date the fever began) — this affects the choice of diagnostic test (NS1/PCR vs. antibody testing)
  • Recent travel to tropical or subtropical regions or history of mosquito exposure
• Photos and records to show the doctor during the outpatient visit:
  • Photos of skin rashes or areas suspected of bleeding
  • Symptom-change diary (fever chart, changes in urination/bowel movements, etc.)

Examples of General Questions to Ask the Doctor

• "What tests are appropriate for my current symptoms (blood tests, NS1, PCR, IgM/IgG)?"
• "If I am taking medications (such as blood pressure medication or anticoagulants), should I stop taking them?"
• "What are the criteria for hospitalization, and what symptoms mean that I should go to the emergency department immediately?"
• "What should I adjust at home and what medications should I take to relieve my symptoms?"

Examples of Disease-Specific Questions

• "Can testing distinguish whether this is a primary infection or a secondary infection (how should the IgM/IgG test results be interpreted)?"
• "Could you explain the criteria for hospitalization or transfusion based on the platelet count and hematocrit changes?"

(Note: NS1 antigen testing or blood PCR for the virus is useful for early diagnosis, and IgM/IgG antibodies become detectable several days after symptom onset. During the acute phase, it is important to avoid medications that increase the risk of bleeding and to ensure adequate fluid replacement.)