How we can put an end to dengue
Dengue has become a recurring phenomenon in the capital and many cities across India. It is not only a major health problem but is proving to be a burden on the economy. Globally, some 100 million dengue infections are reported every year. Dengue has emerged as a byproduct of rapid urbanization and industrialization. Changing weather patterns are also leading to higher mosquito populations. Therefore, it is a fallacy to look at dengue as a problem of health sector only. We will have to find solution to this problem beyond more beds, new drugs and vaccines.
Dengue is basically an urban phenomenon though of late it is being reported from smaller towns also as they witness fast urbanization. Mosquitoes carrying disease-causing viruses spread in urban areas conducive for their breeding and transmission. When cities grow, more people move from villages in search of work and economic opportunities. Most such migrants live in urban slums and sprawls that lack basic amenities like water supply and sewage systems. Due to lack of piped water supply, people are forced to store water and sewage gets collected in cesspools and open drains, all of which creates fertile ground for mosquito breeding. The use of water storage tanks and air coolers is also widespread in migrant colonies and slums.
Increased motorisation is indirectly contributing to the problem. More cars in cities means more used tyres. In the absence of credible recycling and buy-back schemes by tyre companies, most used tyres land in dumps along highways, slums and city peripheries. Tyre dumps are known mosquito breeding grounds as used tyres accumulate water.
Climate change is another new factor. While it is too early to say if increased intensity and greater periodicity of vector-borne diseases is a direct impact of climate change, it is certainly an indication of emerging pattern. The Inter-governmental Panel on Climate Change (IPCC) had warned in last report that a rise in surface temperature and changes in rainfall patterns will impact distribution of vectors like mosquito. As temperature changes occur, malaria and dengue-causing mosquitoes will be breed and survive in the hills too. Cases of malaria and chikungunya have been reported from warmer lowlands in the Himalayas in the past few years.
Effective surveillance of mosquito breeding can help prevent outbreaks of malaria, dengue and chikungunya. If mosquito populations carrying disease-causing viruses and their breeding grounds are identified in time, outbreaks can be prevented as demonstrated in experiments done by Pune-based National Institute of Virology in Surat. Some 550 water pools in the city were put under surveillance and 5,000 mosquitoes from these pools were trapped and analysed in the lab for presence of dengue and chikungunya viruses. Mosquitoes from 13 pools were found to be positive for dengue. Using GIS data and climate condition data (altitude, rainfall and temperature), scientists prepared risk maps for two diseases, which showed parts of city which faced greater risk. Such prediction model can very well be attempted in cities like Delhi. Scientists from the Indian Institute of Chemical Technology at Hyderabad have developed software tools to help forecast outbreaks of tropical infections.
Community participation in the prevention plan is a must. People need to be empowered through targeted health communication and motivated to participate in prevention of mosquito breeding. It is often seen that government buildings, neighbourhood markets, backyards of schools and community centres (even health facilities), bus stands, disused open spaces are turned into dump yards. Even a little rain or spillage of water from overhead tanks or a leaking pipe can turn such places into breeding grounds of mosquitoes. It is here that a vigilant community can alert authorities or take local remedial measures.
A combination of scientific knowledge, software tools, administrative measures and community participation can help prepare cities for the challenge posed by mosquitoes.