Dengue should be prevented and not merely tackled when the epidemic sets in

Indian Express, 30th July 2016

In India, prevention of dengue is left largely to households, while the government offers a cure. (Source: Illustration by C R Sasikumar)

As hoardings across Delhi indicate, we are waiting for a dengue outbreak. Aedes aegypti, the mosquito that carries dengue, is also the carrier of zika - and chikungunya. Just as in case of dengue, India will offer a fertile ground for zika - the deadly virus that deforms babies when it infects pregnant women.

The eggs of the aedes aegypti survive the Delhi cold, the heat and the dryness for more than a year. When the right temperature and moisture conditions come in late summer and during the monsoons, they hatch. The larvae live in freshwater in tanks, ditches, pots and planters all around us. Eggs laid by an infected female mosquito carry the infection. Soon the Delhi air will be thick with dengue-infected mosquitoes. Dengue cases will be on the rise till October.

It is not as if the problem or the solutions are not known. Countries across the world, including poor ones, have attacked the aedes aegypti. Communication campaigns about cleanliness, insecticide-laced mosquito nets and repellents, while important, are not enough. This is particularly so in the case of dense urban communities. The adult mosquitoes fly up to 400 meters. No single household will bear the cost of cleaning all containers and treating water tanks and coolers in its vicinity. Communication is often inadequate as a strategy. For example, it is advised that all water tanks be emptied, cleaned and refilled every week. How many households, given the water situation in Delhi, will be willing to empty out their tanks every week? If your neighbour does not kill the larvae in her tank, you can be infected with dengue. If you live in a student hostel, there is little that you can do. In other words, the prevention of dengue is a public good; it has externalities.

Experts emphasise government intervention and a multi-pronged attack on the aedes aegypti. Fogging is not enough as it attacks adult mosquitoes and not the larvae. Everyday now, larvae will be turning into pupae and then into adults. You cannot do fogging every day, nor is it safe or economical to do so. One important line of attack is to kill the larvae before they develop into mosquitoes.

Internationally, one of the most important interventions for dengue control has been larvicide or killing the larvae in various water bodies. Even if one imagined that somebody would do all this personally to prevent dengue, it is hard to imagine that people would allow someone to walk into their houses and put chemicals into their overhead tanks. That would not be safe as well. For instance, the dosage of temefos, a WHO-approved larvicide that can be added to potable water, must not exceed certain levels.

Clearly government intervention is required. Community participation is required, but preventing dengue cannot be left to communities. Governments need to have a strategy after studying the pattern of the disease and examining ways of attacking it. The prevention of vector borne diseases has been a clear case of intervention in public health all over the world.

In India, prevention of dengue is left largely to households, while the government offers a cure. It offers tests and hospital beds, a strategy that is not only insensitive when compared with the benefits of a public health prevention strategy, but also costly. A number of studies across the world have shown that intervention by governments through a strategy of prevention is cheaper compared to the government paying for the costs of tests and hospitalisation.

Unfortunately, the Indian health establishment's prime focus has been on healthcare. There is an attitude of letting people get sick, and then thinking about how to setup healthcare facilities to treat them. From a public finance point of view, however, it is much better to engage in traditional public health interventions which emphasise public goods. In this case, the critical public health interventions are focused on mosquitoes.

We don't need to wait for newspaper stories about people dying of dengue in order to know that the epidemic of October is on its way. We will get a surge in October 2016. The time to act on these is now, and actions should be grounded in public health and not in healthcare. Unsystematic fogging or only cleaning riverbanks is not going to be enough. It is necessary to embark on comprehensive public health initiatives in July, instead of waiting till October and trying to deal with a surge of sick people using a creaking healthcare system.

Public health today barely accounts for 10 to 20 per cent of most state governments' expenditure on health. Healthcare accounts for 80 per cent to 90 per cent of such expenditure. From a financial point of view, however, healthcare is very inefficient when compared with public health. The effectiveness of public expenditure is dramatically superior when money is spent on well managed public health programmes as compared with spending money on well-managed healthcare. But public health requires a different set of skills. In the example of dengue, attacking mosquitoes requires the state to manage hundreds of health workers walking over every square metre of the area. Public health requires management skills to handle large forces of field workers who perform simple actions reliably. As part of the degradation of the India's state capacity in recent decades, we have become pessimistic about our abilities in public health. In despair, we have emphasised healthcare.

There are epidemics that ambush us, and there are epidemics that we can foretell. North India will have an epidemic of dengue fever in October 2016, as it does every year. The question is: Will we able to rouse ourselves, and have public health interventions ahead of time?

(This article first appeared in the print edition under the headline "Public health, not healthcare")

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