Causes of Dengue

Dengue is caused by a virus carried by one very specific mosquito - and nearly everything about preventing it comes from knowing that mosquito's habits.

The virus and its carrier

• Dengue virus has four types (serotypes DENV-1 to 4) - any of them can cause the illness
• The carrier: the Aedes aegypti mosquito (also Aedes albopictus) - the black-and-white striped "tiger" mosquito
• The mosquito picks up the virus biting an infected person, then passes it on with its next bites - person to mosquito to person
• Dengue does NOT spread person to person directly - no touching, sharing food, or coughing transmission

The mosquito's habits (the prevention blueprint)

• Day-biter: unlike malaria mosquitoes, Aedes bites mostly in the early morning and late afternoon - daytime protection matters
• Clean-water breeder: it lays eggs in clean stagnant water - cooler trays, flower pots, buckets, old tyres, overhead tank lids, money plant vases - not dirty drains
• Short flight range: the mosquito biting you was usually born within your house or a neighbour's - your own surroundings are the battleground
• Urban disease: thrives in cities and towns where stored water is everywhere

Why some fevers become severe

• A second dengue infection with a DIFFERENT serotype carries a higher risk of severe dengue - the immune system's memory of the first can worsen the second
• Children, pregnant women, the elderly, and people with diabetes or other chronic illness face higher complication risk

Season and timing in India

• Peaks during and after the monsoon (July-November) when water collection is everywhere - but in warm cities it circulates nearly year-round

One-line summary

Dengue is a virus spread only by the striped Aedes mosquito - a day-biting, clean-water breeder born in your own stored water - with four virus types, second infections carrying extra risk, and monsoon months as peak season.