Overview#
Dengue fever is an acute viral infection transmitted by the Aedes aegypti mosquito, which breeds in stagnant water and bites primarily during the day. India reports over 100,000 cases annually, with outbreaks peaking during and after the monsoon season (July-November). There are four dengue serotypes (DENV 1-4); infection with one serotype provides lifelong immunity to that serotype but increases the risk of severe dengue (dengue haemorrhagic fever) upon re-infection with a different serotype. Dengue is endemic across most Indian states.
Causes & Risk Factors#
- Aedes aegypti mosquito bite – the primary vector; breeds in clean stagnant water (flower pots, tyres, coolers, overhead tanks).
- Monsoon and post-monsoon season – peak transmission during July-November in most parts of India.
- Urban areas – higher mosquito density due to construction sites, water storage practices, and poor drainage.
- Previous dengue infection – re-infection with a different serotype increases risk of severe/haemorrhagic dengue.
- Children and elderly – at higher risk of complications.
Signs & Symptoms#
- High fever (40 °C / 104 °F) with sudden onset
- Severe headache, especially behind the eyes (retro-orbital pain)
- Intense muscle and joint pain ("breakbone fever")
- Nausea, vomiting, and loss of appetite
- Skin rash appearing 2-5 days after fever onset
- Mild bleeding – nosebleeds, gum bleeding, easy bruising
- Fatigue and weakness lasting days to weeks after recovery
- Warning signs of severe dengue: persistent vomiting, abdominal pain, bleeding from gums/nose, blood in vomit or stool, restlessness, rapid decline in platelet count
Diagnosis#
- NS1 Antigen Test – positive in the first 1-5 days of fever; the best early diagnostic test. Book Dengue NS1
- Dengue IgM and IgG Antibodies – IgM becomes positive after day 5; IgG suggests past or secondary infection.
- Complete Blood Count (CBC) – falling platelet count (< 100,000/µL) and rising haematocrit are key monitoring parameters. Book CBC
- Liver Function Test – AST and ALT are often elevated. Book LFT
- Daily CBC monitoring is essential during the critical phase (day 3-7 of illness).
Treatment Options#
There is no specific antiviral for dengue. Treatment is supportive:
- Hydration – oral rehydration (ORS, coconut water, soups) is the cornerstone. IV fluids for patients with persistent vomiting or signs of dehydration.
- Paracetamol for fever and pain – do NOT use aspirin, ibuprofen, or diclofenac (NSAIDs increase bleeding risk).
- Platelet monitoring – platelet transfusion is only needed if count falls below 10,000/µL or there is active bleeding; unnecessary transfusion carries risks.
- Rest – avoid strenuous activity during recovery; fatigue may persist for 2-4 weeks.
- Papaya leaf extract – some Indian studies suggest it may help improve platelet count, but it is not a substitute for medical care.
Prevention#
- Eliminate mosquito breeding sites – empty and clean water coolers, flower pots, and water tanks weekly. Cover water storage containers.
- Personal protection – use mosquito repellents, wear full-sleeved clothing, and sleep under mosquito nets or in rooms with screens.
- Fogging and larvicidal measures – support community mosquito-control programmes.
- Aedes mosquitoes bite during the day, especially early morning and late afternoon – be vigilant during these times.
- There is currently no widely available dengue vaccine in India (Dengvaxia has limited applicability).
When to See a Doctor#
Consult a doctor for any fever lasting more than 2 days during monsoon season. Seek emergency care immediately for warning signs: persistent vomiting, severe abdominal pain, bleeding, restlessness, cold/clammy skin, or a rapid drop in platelets below 50,000/µL. The critical phase (day 3-7) requires close medical monitoring – do not wait for improvement at home.