Rain creates more dengue breeding grounds

CHENNAI: The incessant rain has done something the state health department has been struggling to do for nearly seven months – wiped away

dengue

mosquitoes and eggs – at least for the time being. But these mosquitoes may have a fine breeding ground if the stagnant water is not cleared up soon, say public health experts.

The ‘aedes’ mosquito which breeds in stagnant water across the state, seems to have lost its battle to nature’s fury. Hospitals from across the state, including Chennai, Kancheepuram and Tiruvallur, have reported lesser dengue cases in the past week. "Rain disrupts stagnant water where mosquitoes lay eggs. This inhibits mosquito activity at least for the next few days," said state chief entomologist Abdul Kader. "But that doesn’t mean people can drop their guard," he quickly added. Rain usually lead to increase in mosquito population.

Though the number of adult mosquitoes comes down during monsoon, a majority manage to survive when they are out in the rain, say entomologists. For a mosquito, getting hit with a raindrop is the equivalent of a human getting hit by a 3,000kg – the weight of an Asian elephant.

Despite the barrage of water droplets, studies published in the proceeding of the

National Academy of Sciences of the USA

show how mosquitoes manage to survive by not resisting rain. "Most mosquitoes don’t venture out during rain. They stay indoors or gather thick foliage. But they survive even when rain drops fall on them," said

Vector Control Research Centre

director P Jambulingam. They may be pushed down by a raindrop, but many manage to get away before they actually hit the ground. "They are light weight and they go with the flow. They never fight the droplet," said Jambulingam.

For these adult female mosquitoes rainwater collected in gardens and open spaces are perfect

breeding grounds

. The female mosquitoes will lay their eggs in these fresh waterbodies. Young mosquitoes will spend about 10 days in water before they are ready to suck blood. The bottom line is to not let water collect in unused containers, say health department officials.

But until then, the focus for the directorate of public health would be to prevent water-borne diseases such as cholera and diarrhoea. "We are telling people to wash their hands, drink clean water and eat freshly cooked food," said director of public health Dr K Kolandaswamy. An advisory by the state government asks people to boil drinking water and avoid cut fruit or vegetables by street vendors.