The World Health Organization (WHO) has assessed Bangladesh's dengue risk at the national level as 'High'. But even before WHO's issuing the high risk alert, there was no doubt in anyone's mind that Bangladesh is experiencing the worst episode of dengue outbreak since 2000 when this mosquito-borne viral disease first struck in recent memory infecting some 5,500 with a death toll of 93. Since then, the disease never left the country, though the number of dengue patients (those hospitalised) and the attendant death toll varied.
There were also years, for example, between 2007 and 2010, when dengue did visit the populace, but not a single death was reported. The same happened again in 2014. But those were exceptional years until the big shock came in 2019 when the infection from the disease reached epidemic proportions with more than 100,000 patients hospitalised among whom 169 patients died of the disease. The next two years the country saw fewer infections and deaths from dengue, though the 2023 is yet another year that is comparable to 2019, but deadlier in that the death figure has already far outnumbered that of 2019 {at387 out of more than 82,500 hospitalised, till August 12, according to Directorate General of Health Services (DGHS)}. However, last year (2022) was also another deadly, dengue-devastated year with 281 deaths, while the total number of infections was fewer at over 62,000. Clearly, from the last few years' record, it appears dengue is getting deadlier by the day. For the proportion of deaths from dengue is on the rise, which is close to 5 per thousand and, perhaps, the highest in the world so far. This is concerning. The only way to prevent the disease is by killing the mosquito, Aedesaegypti, and destroying its breeding grounds. But, to all appearances, the agent of dengue, the Aedes mosquito, is giving the two city corporations responsible for eradicating it real hard time. A recent report says that the bottled insecticide belonging to the Pyrethroids group, an organic compound toxic to mosquitoes, bees and different kinds of flies, but not to humans, is not working well in killing the Aedes mosquito. In fact, according to media reports, experiments done in Australia have shown that after application of the commonly used liquid insecticide, 74 per cent of the flying or resting Aedes mosquitoes bred from egg taken from Dhaka somehow survived. But 100 per cent of the Australian variety of the mosquito died following administration of the toxin. That means, somehow, the Aedes mosquito of Dhaka or of Bangladesh has become insecticide-resistant. This is yet another bad news for the worsening public health situation of the country attributable mostly to the vector-borne disease, dengue. A similar view has been expressed also by an entomologist of Jahangirnagar university, Mr Kabirul Bashar. According to him, the previous notion that Ardes mosquito lays its eggs in clean water is no longer valid. The mosquito has learnt to adapt to new conditions as it has been found to be laying eggs in dirty, even salty water. Even worse, it has also learnt to bite at night (earlier it was thought that it bites only during daytime).
Now with dengue spreading fast in Dhaka and other parts of the country, the challenge before the country's health authorities is enormous. So is it with the local government bodies engaged in combating the mosquito causing the disease.
Seeing that the mosquito is changing its behaviour and becoming resistant to some existing toxins, new strategies have to be evolved to fight it. It calls for conducting researches, if necessary with international support, to devise ways to eliminate Aedes mosquito from its breeding grounds.
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