Monsoon and the mosquito menace

Mosquitoes are a pest with no equal. Though not all mosquitoes transmit life-threatening diseases, those that do kill approximately 725,000 people worldwide every year. When not fatal, the diseases mosquitoes spread can result in bouts of debilitating fever, nausea and vomiting, compromising immune systems and disrupting economies. The WHO South-East Asia Region is particularly affected.

Dengue, chikungunya and malaria are all endemic to the region. These three mosquito-borne diseases threaten the health and welfare of more than 1.4 billion people region-wide. And the first two of them are transmitted by the Aedes aegypti mosquito, which can also spread Zika and yellow fever – diseases that threaten to take root.

As the monsoon washes across the region, mosquito populations must be controlled. The best way to do so is by limiting breeding opportunities and mitigating human-mosquito contact. 

Each of us can take action. Household features such as gutters, uneven concrete, pot plants and spare or discarded tires are all possible water catchment areas. With some mosquito larvae needing just one inch of water to develop into disease-carrying adults, it is essential these sites are monitored and standing water is disrupted wherever it gathers. And it is essential this happens on a weekly basis.

Responsible waste disposal is likewise critical. Non-biodegradable items of household waste – or solid waste – should, wherever possible, be limited, with the rule 'reduce, reuse, recycle' applied as much as practicable. When discarding waste, do so in sealed plastic bags to avoid containers becoming unintended breeding hot-spots. Also ensure the waste is collected by authorities in a timely fashion.  

Households that lack access to piped water must take special precautions. Water storage containers should be fitted with tight lids, with care being taken to restore lids after every use to avoid mosquito infiltration. Where storage vessels rely on rainwater, a fine-mesh covering should be fitted to keep mosquitoes out. Cooperation with authorities carrying out house-to-house water treatment with approved chemical or biological materials is likewise necessary to keep households and neighbourhoods safe. Wherever possible, piped water should be accessed and used, with authorities recognising that a steady water supply is integral to the public's health.

There are other ways that we can limit our exposure to mosquitoes and halt the spread of mosquito-borne pathogens. Key initiatives include wearing light-coloured, long-sleeve clothes, using approved insect repellent and sleeping under a bed net. Windows and doors should be fitted with screens, and householders should consider using approved insecticide sprays or vaporisers in and around their dwellings. By providing mosquitoes fewer opportunities to bite us, we not only protect ourselves from life-threatening diseases, we also limit their circulation. That makes everyone safer.

In keeping with this higher purpose, we must encourage our neighbours and communities to mobilise. Though each household can limit the number of mosquitoes in its immediate vicinity, more far-reaching progress requires greater participation and commitment. Like the neighbourhood watch systems designed to protect property and public safety, we must develop greater cohesion in protecting ourselves against mosquitoes and the diseases they carry. Potential mosquito breeding sites in public spaces such as parks, playgrounds, community centres and markets must be identified, eliminated and brought to the attention of authorities for lasting solutions.

Governments have a responsibility to act. Immediate steps to vanquish mosquito populations – including space spraying and the targeted use of larvicide – are important. But strategies to compromise mosquitoes' long-term future in and around human settlements are the only way to ensure lasting gains. The collapse of earlier mosquito control efforts is testament to the need to modify our environments, and to do so permanently.

In both rural and urban areas, this means improving and expanding domestic water supply to ensure that every household has access to potable water. It means providing more frequent and reliable waste management services that ensure household and industrial waste are disposed of swiftly and responsibly. And it means draining mosquito-breeding cesspools that render life-threatening diseases a fixture of modern life.

Aside from protecting health, the economic gains will be significant. Every year, mosquito-borne illnesses account for millions of lost working hours and foregone earnings. Treatment also incurs direct and indirect costs, which are then borne by individuals and wider society. By investing in sustainable mosquito control measures, governments can not only save lives, but can avoid these costs and the economic burden they represent.

As the most capable and distinguished scientific minds work to find new ways to prevent and treat mosquito-borne diseases, it is imperative that we don't lose sight of our own capacity to act. Each one of us can greatly reduce mosquito populations and our exposure to the diseases they carry. And governments can support these efforts with targeted interventions that permanently modify our cities and towns. 

As monsoon deepens and emerging mosquito-borne diseases threaten to take hold, now is the time to act. Now is the time to make decisive, lasting gains in the struggle to prevent life-threatening mosquito-borne diseases such as dengue, malaria, chikungunya and Zika.



The writer is Regional Director, WHO, South-East Asia Region.