A menace quite manageable
Despite all the racket over the city corporation elections, residents of the capital are unlikely to miss the annoying and lingering whining near the ear ending in bites on exposed skin and itchy swellings.
Tending to come out at dusk, dawn and in the dark, only females of these flying insects have been preying on generations of the young and old year round, sucking blood to develop their eggs.
Some of the 12 species in Dhaka, among the 115 found around the country, are even dreaded for transmitting through their saliva some serious, even life threatening diseases like dengue, which the Directorate General of Health Services says claimed 105 lives since 2002.
With humid conditions in an ever growing urban habitat providing an increasingly hospitable sanctuary for the menace, is there nothing to be done except to sit back and keep swatting at the persistent pests?
Or is there hope the new city corporation mayors can bring an end to it?
Surprising as it may seem there is a crucial role that can be played right at home with the answer to the problem lying with where and how mosquitoes breed and live.
Culex or the species comprising 90 percent of what plagues the city is unique for the fact that its two-week lifecycle can begin with the eggs being laid even in the dirtiest water, provided it is stagnant.
Infestation, irrespective of day and night, drops from January to May, stays constant till July and then rises till December. It primarily poses the threat of filariasis, an infection with filarial worms transmitted through its bites.
The other most common type, aedes, recognisable for their white stripes, requires the same period but prefers fresh standing water, especially that collecting right after rains, near and in households where darkness prevails.
It tends to feed during the day, with the frequency rising till June and then dropping again. This is the species blamed for spreading dengue.
The scourge gets adequate opportunities to multiply in the dense urban habitat, characterised by mindlessly discarded garbage providing nooks and crannies full of endless pools, which also clog drains to create yet more stagnation.
Any place is fair game, be it homes, offices, business centres, bus stops, train stations, launch terminals and any bit of open place. Easy targets are squatters and security guards who are exposed to the elements.
Last winter was painful, be it indoors or outside, with complaints coming up from dwellers around the capital from Uttara to Shyampur, Khilgaon to Gabtoli, not to mention posh neighbourhoods like Gulshan and Banani.
Most blamed the irritant for lack of initiatives from the city corporations.
“In the last two years, I did not see any anti-mosquito drive as there is no councillor for which we have none to complain to,” said Lalmatia resident Mahbub. Right as the sun sets, his last resort is mosquito repellent coils.
Nor is it easy for students, especially SCC and HSC candidates, who say the irritant frequently interrupts their focus and concentration.
“I go inside a mosquito net right after sunset to study,” said Reza-e-Noor Lubana, a SCC candidate of Agrani Girls High School living in Lalbagh.
Though winter has passed, Mirpur-12 resident Mughdha says it is unbearable keeping the doors and windows shut in the hot, humid weather to keep the pests at bay.
The silver bullet, according to Associate Prof Kabirul Bashar of Jahangirnagar University's zoology department, is integrated vector management comprising chemical and biological control and a little awareness on the part of the city dwellers.
Chemicals available in the market attack the mosquito's nervous system, causing hyperexcitation leading to death.
But he says the evolutionary survival tactics of immune systems in mosquitoes long ago kicked in, bringing permanent genetic and olfactory changes over the generations.
Except one or two brands, third generation insecticides available in markets nowadays just block off their synapses for a while, making them dizzy.
Foggers are worse, he says, with an efficiency rate of merely about 20 percent and only driving mosquitoes into homes and other places where the smoke cannot reach.
He suggests the city corporation test insecticides every two years for their effectiveness and checking for active ingredients in the bulk purchases.
On biological control, he says guppy fish, introduced in 2000, turned out to be a huge success in the crackdown on larvae. Similar benefits come from mosquito fish or Gambusia and toxorhynchites or elephant mosquito whose larvae feed on that of other mosquito species.
However, there is a catch. The fish do not stay in excessively polluted water while it is practically impossible to reach and release them in all stagnant pools.
Planting marigolds, catnip and scented geraniums are also reputed to keep the mosquitoes away.
The most important role is of the city dweller, who should practice the habit of cleanliness around the house and beyond, properly disposing all items that can collect water, keeping drains free flowing, and using mud to cover up tree holes and bamboo stumps.
Raising awareness is also a key. He even recommended imposing fines on households failing to keep to the hygiene code.
Bites can be avoided wearing chemical repellents like those containing DEET (N,N-diethyl-meta-toluamide) or natural oils like that of citronella, cinnamon and castor; avoiding heavy dark clothing and staying cool, for mosquitoes are attracted to warm bodies.
There is even the insecticide fendozin-rich net, produced by BASF and Grameen Healthcare Trust, which kills mosquitoes and other bugs within 20 minutes after they come in contact with it. Effective up to 20 washes, the net costs Tk 650 to 700.
Homes can also be made insect-proof with screens.
Armed with a budget of Tk 20.3 crore, both city corporations in Dhaka blame understaffing as their key barrier.
“There is only five to seven staff in each ward that requires 20 to cover the entire area,” said Dhaka North City Corporation (DNCC) Chief Health Officer Brig Gen AKM Masud Ahsan, adding they were working on cleaning water bodies.
His counterpart in the south, Brig Gen Md Mahbubur Rahman, said they were already armed with 4,000 litres of adulticide while another 20,000 litres were on the way.
DNCC Senior Entomologist Mohammad Alam Sharif Khan said they test larvicides and adulticides at places including Khamar Bari's Plant Protection Wing and in the field before finalising the purchase.
Newspaper advertisements will also be published to aware people against dengue, he said.
Whether this would truly bring about a positive change and whether mosquitoes will continue to be a nuisance rather than a serious threat can be only found out in the days to come.
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