PREVENTION OF DENGUE THROUGH SAVING SKIN FROM MOSQUITO BITE

Dengue in Bangladesh has been a nagging problem for the past few years with varying intensity over months. But sustainable control is yet far away. Rigorous attempts to control dengue have been limited to clean water hyacinths in ditches and ponds, stagnant water from flower pots, coconut shells, drains, tyres, etc. which are accumulated and encourage mosquito breeding. It is an established fact that vector-borne diseases are better controlled by killing vectors. It is not known whether any research conducted to control mosquitoes in ponds, ditches, small or big water bodies, derelict ponds and changes in population density of mosquitoes in those areas. Obviously, population density will be more in ponds and other small or big water bodies than in flower pots on roof tops, tyres etc. Even if water hyacinth is cleaned, the larvae remain quite homely there. 

Chemicals that kill larvae are called larvicides. Media reports say larvicide does not work. But the scientific reasons for failure have not been unearthed. The scientific reasons for failures have been discussed in two publications (Miah 2023, Miah 2024). According to WHO protocol, mosquito larvae are released in containers having different concentrations of larvicides. The larvae are surrounded by larvicides, and obviously they will die. These larvicides, when sprayed on larvae living above the ground, will be contaminated leading to mortality. But the biology of mosquitoes is different. They breed in water and larvae and pupae live under water, only they move to the water surface for breathing. 

One aspect has been overlooked all the time because of the knowledge gap. Standing water in irrigated Boro rice field, which is clear, is a safe place for breeding of mosquitoes. Large scale adoption of the technique of Alternate Wetting and Drying (AWD) developed by International Rice Research Institute in water management is good enough to tackle this. The Department of Agricultural Extension under the Ministry of Agriculture is quite familiar with this technique.

The larvicide sprayed on water bodies cannot reach mosquito larvae living under water. The above two publications are based on 100 years old publication of works where soybean oil thinly poured in water created a thin oily film on water surface and caused suffocation to mosquito larvae and pupae. To implement that f inding, simply soak sand or soil in soybean oil and throw those at random as sand balls over the whole water body. Larvae and pupae of mosquitoes, when coming up to water surface for oxygen uptake through their spiracles located at the tip of abdomen, cannot pierce through the oily film to inhale oxygen. As a result they die of asphyxiation (suffocation). Since oily film will disrupt surface tension of water, adult mosquitoes trying to land on water surface will have their legs dipped in water and be stuck to die (Miah 2023, Miah 2024)

Since available larvicides are ineffective, there is dire necessity to look for alternative larvicides. News media publicize prevalence and apprehend cause of mosquito population. But there is hardly any research or message on killing mosquitoes and protection of skin from mosquito bites under Bangladesh environment .In the prevailing circumstances, in addition to treatment in the hospital, a concerted effort is warranted at national level, community level in urban, periurban and rural level to control mosquito as well as to save skin from mosquito bite as preventive measures. These deserve a top priority attention to put dengue at bay. Simply hospitalization is not a sustainable strategy at all to get rid of dengue in the country.