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Updated: November 5, 2012 17:51 IST

Ways and means to wipe out deadly dengue

Shastry V. Mallady
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Stagnating drain water at the refugee camp in Anaiyur on Sunday is a perfect breeding ground for mosquitoes. Photo: G.Moorthy
Stagnating drain water at the refugee camp in Anaiyur on Sunday is a perfect breeding ground for mosquitoes. Photo: G.Moorthy

The female aedes aegypti mosquito feeds during the day, says paediatrician

Dengue fever is the hot topic in Madurai now. As fever cases go up, health authorities and the district administration have taken up mosquito control measures on a war-footing especially in the Melur block.

Since the prevention of dengue fever is directly linked to public awareness on eradicating mosquito breeding sources, a paediatrician in Madurai S. Naavarasu has explained the why, when, how and where about dengue so that people can take precautions at home.

Breeding sources

Dengue is a mosquito borne febrile viral illness and the infection is spread to humans by ‘aedes aegypti’ mosquito which feed during the day. Rarely is the dengue infection spread by ‘aedes albopictus’ mosquito.

Artificial manmade containers are breeding grounds and sources include flower vases and pots, basins, water jars, discarded items lying in the backyard of house, air-conditioner tray, roof gutters, cisterns and concrete drains. The natural containers where the dengue-causing mosquito breeds are tree holes, bamboo stumps, leaf axils and fallen leaves.

“All these sites require constant inspection and it is advisable to change the water in flower vases on alternate days. We should also turnover all water storage containers,” says Dr. Naavarasu.


He advises that everyone, particularly children who are getting affected, should use long sleeved shirts, shoes and long pants in this season. Mosquito nets, repellents and mosquito coils are highly recommended. Water stagnation must be avoided in and around the house.

“Dengue infection causes illness ranging from relatively mild fever to severe haemorrhage leading to death. Dengue hemorrhagic fever and dengue shock syndrome needs hospitalisation. Substandard living conditions and lack of vector control measures are among the important causes of dengue infection,” the paediatrician explains.

Aedes aegypti mosquito is adapted to breed around human dwellings.

“Only the female mosquito feeds on blood because they need the protein found in our blood to produce eggs. Male mosquitoes feed on plant nectar. Aedes are day-biters and are most active during dawn and dusk time,” Dr.Naavarasu said.

One distinct physical feature of aedes mosquito is its black and white stripes on its body and legs. On an average, a female aedes mosquito can lay about 300 eggs during her life span of 14 to 21 days. Adult mosquitoes shelter indoors and bite during one to two hour intervals in the morning and late afternoon. Dengue virus has four distinct serotypes and humans are the main reservoir for dengue virus.

Prevention is not just about eradicating standing water. It is true
that water collection points are where the mosquito hatches but it
only ‘collects’ the virus when it bites an infected person –us!
Dengue can only be caught from other human beings –not directly but
through the carrier / vector - which is the mosquito.
We are all potential sources of the disease. Through my company's work with natural mosquito repellents I am very aware of the dangers associated with dengue fever and am rather surprised at some Governments and medical authorities lack of
information and effort to make sure the patient is not bitten again
- and thus keep propagating the disease.
The issue is that whilst the patient is running with a temperature in
the febrile stage he or she is acting as a massive multiplier and
reservoir of the Dengue virus, and when bitten at this stage by
another mosquito then the disease spreads.
An air conditioned room will keep away most mosquitoes, however
without that luxury one must protect the patient AT ALL TIMES with
repellent. The problem is that the active chemical ingredient DEET
used in most repellents is not to be used too often or over applied,
particularly to younger patients. The other problem is that DEET
products tend to be rather oily, somewhat harsh on the skin and
certainly uncomfortable to 'wear' all day -and it has to be all day
for the Dengue fever carrier - Aedes aegypti - is active all day and
not just at dawn and dusk as with most species of mosquito.
One answer is a personal repellent proven effective against Aedes
aegypti that can safely and comfortably be worn all day with
absolutely no harmful chemical build up. You may well have guessed my
company has such a product and we would love to think we could help
stop the spread of the disease from the patient whilst also being the
first line of defence for the nursing staff. It seems strange to us
that even the World Health Organisations advice on caring for Dengue
fever patients does not include the simple advice of protecting the
patient from further bites, which of course is where the mosquito will
get more 'ammunition' for its sometimes deadly work.

from:  mike harrison
Posted on: Nov 5, 2012 at 15:11 IST
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