Dengue is transmitted by Aedes mosquitoes, particularly A. aegypti and A. albopictus.So it is very important for us to know about these mosquitos and to learn how to prevent its breeding in our neighbourhood.
Dengue viruses are transmitted to humans through the bites of infective female Aedes mosquitoes. The mosquitoes generally acquire the virus while feeding on the blood of an infected person. After virus incubation for eight to ten days, an infected mosquito is capable, during probing and blood feeding, of transmitting the virus for the rest of its life. There is no way to tell if a mosquito is carrying the dengue virus. Infected female mosquitoes may also transmit the virus to their offspring by transovarial (via the eggs) transmission, but the role of this in sustaining transmission of the virus to humans has not yet been defined.
After taking a blood meal, female Aedes aegypti mosquitos produce on average 100 to 200 eggs per batch. The females can produce up to five batches of eggs during a lifetime. The number of eggs is dependent on the size of the bloodmeal. Eggs are laid on damp surfaces in areas likely to temporarily flood, such as tree holes and man-made containers like barrels, drums, jars, pots, buckets, flower vases, plant saucers, tanks, discarded bottles, tins, tyres, water cooler, etc. and a lot more places where rain-water collects or is stored. The female Aedes aegypti lays her eggs separately unlike most species. Not all eggs are laid at once, but they can be spread out over hours or days, depending on the availability of suitable substrates. Eggs will most often be placed at varying distances above the water line. The female mosquito will not lay the entire clutch at a single site, but rather spread out the eggs over several sites.
The eggs of Aedes aegypti are smooth, long, ovoid shaped, and roughly one millimeter long. When first laid, eggs appear white but within minutes turn a shiny black. In warm climates eggs may develop in as little as two days, whereas in cooler temperate climates, development can take up to a week. Laid eggs can survive for very long periods in a dry state, often for more than a year. However, they hatch immediately once submerged in water. This makes the control of the mosquito very difficult.
Prevention of breeding of Aedes mosquito
Aedes mosquito lay their eggs in clear,clean water and not in contaminated water.As they fly only a few metres their breeding place is usually in our house itself.
Most common breediing places and tips to prevent breeding
Water storage tank/cistern ---should have mosquito proof lids
water coolers/collection pans in Fridge/ACs ------ water should be drained out periodically
Drum ------tight lids
Flower vase with water [least in brass vase]----------change water frequently,use sand
Potted plants with saucers ------- change water frequently
Ornamental pool/fountain ---------water changed once a week
Roof gutter/sun shades------------check frequently for drain block
Animal water container----------- empty and clean periodically
Ant trap--------------------------use oil/salt
Used tyres-----------------------keep it under roof
Discarded large appliances-------bury or keep it under roof
Discarded buckets,plastic cups,tin cans etc-----bury
Whenever piped water supply is inadequate and available only at restricted hours or at low pressure, the storage of water in varied types of containers is encouraged, thus leading to increased Aedes breeding.It is essential that potable water supplies be delivered in sufficient quantity, quality and consistency to reduce the necessity and use of water storage containers that serve as the most productive larval habitats.
Chemical and biological agents can also be used for prevention of breeding of Aedes mosquito.