Dengue is an acute viral infection with potential fatal complications. Dengue viruses (DV) belong to family Flaviviridae and there are four serotypes of the virus referred to as DV-1, DV-2, DV-3 and DV-4. DV is a positive-stranded encapsulated RNA virus and is composed of three structural protein genes, which encode the nucleocapsid or core (C) protein, a membrane-associated (M) protein, an enveloped (E) glycoprotein and seven non-structural (NS) proteins. It is transmitted mainly by Aedes aegypti mosquito and also by Ae. Albopictus. [1]

All four serotypes can cause full spectrum of disease from a subclinical infection to a mild self limiting disease, the dengue fever (DF) and a severe disease that may be fatal, the dengue haemorrhagic fever/dengue shock syndrome (DHF/DSS). The 1997 WHO classification divided dengue into undifferentiated fever, dengue fever (DF), and dengue haemorrhagic fever (DHF).

Symptoms of dengue illness are:

High fever and at least two of the following:

  • Severe headache
  • Severe eye pain (behind eyes)
  • Joint pain
  • Muscle and/or bone pain
  • Rashes on the skin
  • Mild bleeding manifestation (e.g., nose or gum bleed, petechiae, or easy bruising)
  • Low white cell count

Laboratory: Rapid decrease in Platelet Count

Prevention of Dengue

To prevent dengue fever, you must prevent the breeding of its carrier, the Aedes mosquitoes. Aedes mosquitoes are identified by the black and white stripes on their bodies.

Aedis aegypti : The Mosquito that causes dengue


Under optimal conditions, the egg of an Aedes mosquito can hatch into a larva in less than a day. The larva then takes about four days to develop into a pupa, from which an adult mosquito will emerge after two days. Three days after the mosquito has bitten a person and taken in blood, it will lay eggs, and the cycle begins again.

Did you know?

  • Only the female Aedes mosquito bites as it needs the protein in blood to develop its eggs.
  • The mosquito becomes infective approximately seven days after it has bitten a person carrying the virus. During the seven days period, the virus replicates in the mosquito and reaches its salivary glands.
  • The mosquito Aedis, breeds in fresh water.
  • It is a day biting mosquito
  • The average lifespan of an Aedes mosquito is two weeks.
  • The mosquito can lay eggs about three times in its lifetime, and about 100 eggs are produced each time.
  • The mosquito can breed all through the year. The eggs can lie dormant in dry conditions for up to about nine months, after which they can hatch if exposed to favourable conditions, i.e. water and food.

Dengue Prevention

Dengue prevention is the most important step to reduce the risk of dengue infection. There are several ways of prevention:

Prevention by Mosquito control

The best way to reduce mosquitoes is to eliminate the places where the mosquito lays her eggs, like artificial containers that hold water in and around the home.

In urban areas, Aedes mosquitos breed on water collections in artificial containers such as plastic cups, used tires, broken bottles, flower pots, etc. Periodic draining or removal of artificial containers is the most effective way of reducing the breeding grounds for mosquitoes.

Larvicide treatment is another effective way to control the vector larvae but the larvicide chosen should be long-lasting and preferably.

There are some very effective insect growth regulators (IGRs) available which are both safe and long-lasting (e.g. pyriproxyfen). For reducing the adult mosquito load, fogging with insecticide is somewhat effective.

To eliminate standing water:

  • Unclog roof gutters
  • Empty children's pools at least once a week
  • Change water in birdbaths at least weekly
  • Get rid of old tires in your yard, as they collect standing water
  • Empty unused containers, such as flower pots, regularly or store them upside down
  • Drain any collected water from a fire pit regularly

Prevention by reducing Mosquito bites- Particularly daytime bites.

Prevention of mosquito bites is another way of preventing disease. The adult mosquitoes like to bite inside as well as around homes, during the day and at night when the lights are on. To protect yourself, use insect repellent on your skin while indoors or out, mosquito traps or mosquito nets.

When used properly, repellents are safe for kids and adults alike. Keep in mind that even though some of them are classified as pesticides by the Environmental Protection Agency (EPA), repellents don't kill mosquitoes. So you may still see these annoying insects buzzing about. Repellents simply make it more difficult for mosquitoes to find you.

When possible, wear long sleeves and pants for additional protection. Also, make sure window and door screens are secure and without holes and use mosquito nets.

Clothing tips to keep in mind before entering into a mosquito infested place:

  • Wear long-sleeved shirts, long pants & socks
  • Consider tucking your pants into your socks
  • Wear light-colored clothing, since mosquitoes are more attracted to darker colors
  • Apply mosquito repellent to your clothing, shoes, and camping gear and bed netting
  • Wear a full-brimmed hat to protect your head and neck
  • Consider wearing a mosquito net to cover your head and face or torso