India, since time immemorial, has been fighting to eradicate malaria. In fact, India is one of the first few countries to launch a national programme against malaria. Though the programme has changed its name several times over the last 5 decades, the ultimate goal has always been to get rid of the mosquito menace. Nevertheless, in spite of these strenuous efforts, the mosquitoes have been putting a very tough front in this bio-war. But, we are in a deeper turmoil. Not only have anopheles mosquitoes emerged and established its forts strong, but also other diseases like dengue and chikungunya emerging rampantly and taking a giant leap into the future of tropical diseases. It has long been established that dengue fever is caused by a group of mosquitoes called as Aedes aegypti. Most of us are aware of the symptoms of dengue fever, but very few of us understand the bionomics of these mosquitoes.
First and foremost, it is essential to note that unlike anopheles mosquitoes, Aedes aegypti mosquitoes breed early in the morning. That is an important reason why any control measures like fogging or spraying insecticides should be carried out in the wee hours of the morning. The next important aspect is the place where the Aedes mosquitoes breed. It commonly breeds in stored water. This is where adequate discussion needs to be done. When we mean ‘stored water’ we refer not to the dirty drainage water, but to the clear, clean water that could probably be used for drinking, bathing and other recreation purposes.
Now, how is this important in our lives? All of us use water for our day to day activities and at some point of time we do store water. The concern of this water storage is important in rapidly growing cities like urban areas such as our metropolitan cities like Chennai, Bengaluru and others. In these places, rapid expansion has led to boom in real estates. The end result: constant construction in some part of the city. Now though this might bring happiness to some, it definitely paves way for water storage and thereby enables the mosquitoes to breed. The next point is acute water shortage. This is seen in two extreme forms in an urban setting- First in urban slums, mass dwellings like hostels, mansions, etc where water is stored in an array of plastic pots. These pots, when left uncovered, invite the Aedes mosquitoes to breed. The other end is seen in multi-storey buildings and individual houses where drinking water is partaken from cans. When these cans are left open and unattended, the mosquitoes find its way inside. The next serious issue comes in commercial centres, high-end bungalows, shopping complexes and other recreation centres where water is used for pleasure and entertainment. These include fountains and artificial and aesthetic constructions and placing of plates and dishes beneath the flowering pots, which form a major source of vectors. In certain other areas of the households, and small scale industries and commercial areas, the sources of Aedes vectors are of two major types- one in the form of unused and condemned tyres, and the other, used and discarded coconut shells.
Though most of us might be in a financial position to find treatment for dengue fever when it strikes us, it is all the more important to try to prevent it from occurring. Having detailed so much about the source of vector breeding, how many of us are very sure that none of these above said sources exist in our houses? We have to think hard, for we hardly pay attention to minute details of what lies in the nooks and corners of our houses, workplace, etc. Having said this, let us see how we can get rid of these problems. In a rapidly urbanising city like ours, it is very difficult to avoid storing water for regular purposes like cooking, drinking, etc., but we can always take precautions to keep the containers closed. As far as the recreational water use is concerned, let us design the fountains in such a way that the water keeps flowing through at a constant rate and does not have to stay stagnant for even a minute. And when modern engineering measures are taken, let us make sure that we do not, even by ignorance construct any part, panel or piece of art, which is liable for water accumulation. When we have to place containers beneath the plants to avoid water spillage, let us take adequate measures to drain them periodically and keep them dry. Let us look around our households and discard empty coconut shells, rubber tubings and unused tyres. Let us all take these small and simple measures to clean our own houses and workplaces and thereby fight the first step towards preventing dengue fever. For, the weather change is fast approaching and the chances of the infections due to vectors is round the corner.