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Experts believe prompt action on breeding sites will lessen the mosquito menace during the monsoon
Published : 06 Apr 2025, 03:02 AM
Even in the dry season, Aedes mosquito larvae and adult mosquitoes are being spotted in homes and establishments across Dhaka.
Experts say the presence of Aedes mosquitoes before the monsoon is alarming, considering the number of deaths and infections in the first three months of the year.
They stress the need for immediate preparations to control mosquitoes.
On Mar 24, a three-strong team was seen going door-to-door spraying mosquito repellent in Mirpur’s Lalkuthi.
Two members were searching for mosquito larvae while the third was applying the insecticide.
It was learned that the two searching for larvae were laboratory staff from the Department of Zoology at Jahangirnagar University.
The other person was a mosquito control worker from the Dhaka North City Corporation (DNCC) Waste Management Department (WMD).
The DNCC has partnered with the university to monitor mosquito hotspots across the city.
In a visit to 15 homes in Lalkuthi’s first colony, the team found Aedes larvae in water meters, discarded pitchers, and water storage drums—often left uncovered due to residents’ negligence.
In one tin-shed house in the colony, a pitcher left under a banyan tree had accumulated rainwater over time, becoming a breeding ground for Aedes mosquito larvae."
A tenant of that house told bdnews24.com, "The landlord placed that pitcher under the banyan tree. Perhaps it hasn't been cleaned, which is why mosquitoes are probably laying eggs there."
In another house in the colony, the DNCC workers found Aedes mosquito larvae in two water storage drums.
Diana Akter, the homeowner's daughter, explained that the area's water supply was irregular, necessitating water storage.
"Water comes around 3-4 am. I fill buckets every day and use it for washing dishes. We keep the water covered. I don't understand how mosquitoes still laid eggs there, even with the cover," she said.
At house number 227/D in the same colony, water was stored in both a large and a small bucket in the yard.
Upon inspection, survey workers found Aedes mosquito larvae in both buckets.
The residents whose buckets contained larvae declined to comment on the issue.
Hena Begum, a resident of another flat in the same house, said: "We don't have a motor in our flat, so we can't draw water easily.
“We have to store the supplied water in buckets. I think that's why mosquitoes are laying eggs."
Md Tariqul Islam, a local resident, said: “There are a lot of mosquitoes at home. It’s hard to sleep at night. We use mosquito coils, and set up nets, but still they bite, especially the children.”
To study mosquito trends, species, and seasonal patterns, the DNCC has signed an agreement with Jahangirnagar University’s zoology department.
Five regions have been designated as “sentinel sites” for trapping mosquitoes.
Each site has three types of traps: light traps, Aedes-X smart traps, and gravid traps.
The light trap collects all species of adult mosquitoes.
The Aedes-X smart trap catches adult Aedes mosquitoes, while the gravid trap is designed for egg-laying Aedes females that subsequently produce larvae.
These traps are checked every seven days. The number of mosquitoes found in the traps provides an indication of mosquito presence in that area.
One such sentinel site has been set up at the DNCC’s ward No. 10 community centre in Lalkuthi.
On Mar 24, mosquito control workers checked the traps at the community centre. Hundreds of dead mosquitoes were found in the light trap.
Two adult Aedes mosquitoes were collected in the smart trap, while no larvae were found in the gravid trap.
The team declined to specify the exact number of mosquitoes collected but confirmed the quantity was significant.
SITUATION OVERVIEW
On Monday, during an inspection of 15 homes in the first colony of Lalkuthi, the DNCC workers found mosquito larvae in six containers across five homes.
The data revealed a Breteau Index of 40 and a House Index of 33 for the area.
Entomologists consider any area with a Breteau Index above 20 and a House Index exceeding 10 to be at significant risk for mosquito infestation.
Entomologist Manjur Ahmed told bdnews24.com on Monday, "This is a very high level of presence. There's a risk of mosquitoes increasing further with the forthcoming monsoon.
“Many were affected by Chikungunya last year. This time, the number of Chikungunya cases will also rise alongside dengue."
Kabirul Bashar, a zoology professor at Jahangirnagar University, told bdnews24.com that due to a contract with DNCC, they are unable to provide specific survey data and that inquiries should be directed to the DNCC.
Bashar, however, added: "There is no rain now; if the Breteau Index is 40 now, it will become 80 during the rainy season.
“This means the mosquito presence will be alarming.
“If we can control Aedes breeding sites before the rains, the mosquito nuisance will be reduced during the monsoon season.”
Imrul Kayes Chowdhury, chief health officer of DNCC, claimed that both Aedes and Culex mosquito populations have decreased over the past month.
As a result, the number of dengue cases in Dhaka has also dropped.
He said, "Culex mosquitoes are found somewhat in certain pocket areas, especially in some areas of Uttara. We have taken steps to control mosquitoes.
“Regular mosquito eradication activities are being conducted. Despite this, mosquitoes are breeding in some areas due to people's lack of awareness.
“Many households do not allow mosquito control workers to enter, so how will they administer the insecticide there?"
According to the Directorate General of Health Services (DGHS), the number of dengue patients admitted to hospitals across the country in the 24 hours up to Wednesday, including new admissions, stood at 1,877 in the first three months of the year.
Among them, 13 deaths were reported.
In 2024, the total number of dengue patients hospitalised across the country reached 101,214, with 575 fatalities.
CULEX MOSQUITOES CAUSE GROWING DISTRESS
Culex mosquitoes have plagued Dhaka since winter's end, with residents frustrated by the persistent bites.
City dwellers allege that the increased Culex mosquito infestation is due to the lack of drain and ditch cleaning and insufficient spraying of mosquito repellent.
The lake situated between Bhasantek Government Secondary School and Bhasantek slum is filled with water hyacinth.
This water body is not cleaned, leading to the breeding of Culex mosquitoes in the stagnant water.
Ahmed Ali, a resident of Bhasantek slum, told bdnews24.com: "The mosquito torment starts in the afternoon. There's nowhere you can stand without being bothered.
“They buzz constantly near ears."
Jemmin Akter, a housewife from Mirpur 14, said, “I light a mosquito coil in the house in the afternoon. Before sleeping at night, I extinguish the coil and hang up the mosquito net.
“But even then, there's no escape from the mosquitoes. If I go outside for any reason, mosquitoes get inside. They bite my child more."
Dhaka South City Corporation is not conducting any surveys on mosquito presence.
As a result, the current mosquito situation in that area remains unclear.
Dhaka South City Corporation (DSCC) is not conducting any surveys on mosquito presence, making it hard to gauge the current situation in the area.
A survey, however, conducted in November of last year found that mosquito presence was higher in DSCC compared with the DNCC.
According to that survey, out of the 99 wards in both city corporations, 56 were deemed at risk.
Among them, 35 wards belonged to DSCC while 21 were part of DNCC.
When asked about preparations for preventing dengue Nishat Parveen, chief health officer of DSCC, told bdnews24.com: “The Culex mosquito problem has decreased.
“But the threat of dengue may increase, and we’ve already started relevant activities. Along with spraying insecticides and cleaning, we will also focus on raising public awareness,” she added.
[Writing in English by Sheikh Fariha Bristy]
