Public warned to be extra-vigilant:

Heightened dengue threat

Ridma DISSANAYAKE

* Mosquitoes now breeding in wells

* Sting time too extended

The Health Ministry yesterday warned the public to be extra vigilant concerning the dengue epidemic following new evidence showing the dengue mosquito had taken to breeding inside domestic wells in addition to its normal breeding sources of used receptacles, overhead gutters and discarded tyres .

“The Health Ministry had made the public aware only about water storage containers as mosquito breeding places.

The ministry’s Research Entomological Unit has revealed that dengue mosquitoes have changed their life pattern to counter steps taken for their eradication and have begun laying eggs in wells,” a ministry spokesman said.

The highest dengue mosquito breeding source in the Eastern Province (46 percent) is found to be wells. Mosquitoes are mostly using wells with cement walls to lay eggs.

The Health Ministry has informed the public to breed small fish species in wells to destroy the eggs of dengue mosquitoes, the spokesman said.

He said the public have also been informed the dengue mosquito which was said to be more active from 6am to 10am and from 4pm to 6.30 pm has extended its stinging period to 11pm according to the same research.

Health Ministry entomological surveys have revealed the dengue mosquito is a double breeder and is most powerful of all mosquitoes. According to sources there are more than 2,500 species of mosquitoes worldwide and Sri Lanka is home to 250 such species . Mosquitoes belong to a group of insects that require blood to develop fertile eggs. All, except the dengue mosquitoes, take the blood of all animals and humans. But the dengue mosquito only draws on human blood to help develop fertile eggs.

Dengue mosquitoes have a life span of one month and lay eggs four times during their lifetime. They bite humans more than once. Other mosquitoes have only a one week life span and lay eggs only once. They also bite humans only once. Accordingly, a single dengue mosquito has the ability to spread dengue among a number of persons.

The Health Ministry entomological surveys have revealed that dengue mosquitoes have changed their life patterns resulting in the increased breeding of the dengue mosquito.

The ministry spokesman warned the public to be more careful considering the new developments concerning the dengue mosquito.