Hot weather may fuel dengue cases

Straits Times 15 Jun 12;

THE number of dengue cases fell to a three-year low for the first half of the year, but the current hot weather could push the figures up again.

Heat suits the Aedes mosquito and shortens its growth process, which could send it into breeding mode more quickly, the National Environment Agency (NEA) has warned.

The public should thus be vigilant about preventing the breeding of this mosquito, which carries and spreads the dengue virus, the agency said ahead of Asean Dengue Day, which kicks off today.

In the first five months of this year, 1,529 people came down with the viral illness - fewer than the 1,742 in the first five months of last year and the 1,676 in the corresponding period the year before.

Despite the dip in the number of infections, the public should continue to make sure the Aedes mosquito has no place to lay its eggs by doing what NEA calls the five-step Mozzie Wipe-out.

The steps include changing the water in vases and removing water from flowerpot plates on alternate days.

It was reported last week that temperatures here are expected to soar to 30 deg C at night in the coming weeks. Daytime temperatures could hit 34 deg C.

June is typically the hottest month of the year in Singapore. Average daily temperatures can range from 24.8 deg C to 31.3 deg C.

Studies have shown that warmer weather speeds up the development of mosquito larvae into adults. They reach adulthood in less than 10 days, compared with the usual one to two weeks.

At temperatures of 30 deg C, more female mosquitoes are produced as well. The result is a larger and predominantly female mosquito population, which has to feed in order to breed.

Further, the warm weather helps the dengue virus multiply faster and it will have a shorter incubation period in the mosquito's body.

Dengue is transmitted to humans when they are bitten by infected mosquitoes. The symptoms include a sudden onset of fever, body aches, pains in the joints, loss of appetite and skin rashes.