What is dengue fever?
Dengue fever is a mosquito-borne viral infection caused by the dengue virus (DENV), transmitted by Aedes aegypti and Aedes albopictus mosquitoes. It affects an estimated 390 million people worldwide each year, primarily in tropical and subtropical regions. Most cases cause a self-limiting febrile illness lasting 5–7 days. A small proportion progress to severe dengue (dengue haemorrhagic fever or dengue shock syndrome), which can be life-threatening without prompt hospital care.
Symptoms of dengue fever
Symptoms typically appear 4–10 days after a mosquito bite and include:
- Sudden high fever (39–40°C / 102–104°F)
- Severe headache, especially behind the eyes
- Intense muscle and joint pain ("breakbone fever")
- Skin rash — appears 2–5 days after fever starts
- Nausea and vomiting
- Fatigue and general weakness
- Mild bleeding — nose bleeds, gum bleeding, easy bruising
⚠ Warning signs — go to hospital immediately
- Severe abdominal pain or tenderness
- Persistent vomiting (3+ times in 24 hours)
- Bleeding from gums, nose or in vomit/stool
- Rapid breathing or difficulty breathing
- Feeling very restless, confused or drowsy
- Platelet count below 20,000/μL
Dengue blood tests explained
| Test | When to use | What it detects |
|---|---|---|
| NS1 Antigen | Day 1–5 of fever | Dengue virus protein — best early test |
| IgM antibody | Day 5 onwards | Recent dengue infection |
| IgG antibody | Secondary infections | Past dengue exposure |
| CBC (Platelet count) | Daily monitoring | Falling platelets = dengue progression |
| Haematocrit (PCV) | Daily monitoring | Rising haematocrit = plasma leakage (danger sign) |
Platelet count in dengue
| Platelet Count | What it means | Action |
|---|---|---|
| > 100,000/μL | Mild drop | Monitor daily, rest at home if no warning signs |
| 50,000–100,000/μL | Moderate drop | Hospital assessment recommended |
| 20,000–50,000/μL | Severe drop | Hospital admission required |
| < 20,000/μL | Critical | Platelet transfusion may be needed |
What to do if you have dengue
- Rest: Complete bed rest is essential during the febrile phase
- Hydration: Drink at least 2–3 litres of fluids daily — oral rehydration salts (ORS), coconut water, clear broth, fruit juices
- Paracetamol only: Take paracetamol (acetaminophen) for fever and pain — do NOT take ibuprofen, aspirin or diclofenac (they increase bleeding risk)
- Monitor platelet count: Daily CBC from day 3 of fever
- Watch for warning signs: Go to hospital immediately if any danger signs appear
- Mosquito control: Use mosquito nets and repellent to prevent spreading dengue to others
There is no specific antiviral treatment for dengue
Treatment is supportive — managing fever, maintaining hydration and monitoring for complications. Dengue vaccines exist (Dengvaxia) but are only approved for people with previous dengue infection. Research into better vaccines continues. Prevention through mosquito control remains the most important public health tool.
Questions to ask your doctor
- Should I be admitted to hospital with this platelet count?
- How often should I recheck my CBC?
- When is it safe to return to work or school?
- Can I give dengue to family members at home?