Waste-filled drains, canals, ineffective chemicals plague mosquito control efforts

On the morning of 23 November, a larviciding operation was conducted in the Rajarbagh, Kalibari Temple area of Ward 5, Dhaka South City Corporation. Mosquito control workers targeted waste-filled canals and nearby areas, with the operation live-streamed on Facebook by the city corporation.

Locals, however, questioned the effectiveness of the effort – the waste had not been cleared beforehand, they argued.

While larviciding and fogging are carried out once or twice a month, there's no visible effort to remove waste from the canals and drains, Subhankar Roy, a local shopkeeper, told TBS.

He further questioned the effectiveness of applying insecticides on unclean surfaces, saying, "Waste accumulates in the canals and drains, but they remain uncleared before being sprayed with insecticide."

This reporter observed similar scenes after visiting at least 20 areas within Dhaka's two city corporations, including Mirpur, Mohammadpur, Old Dhaka, Jatrabari, Sayedabad, Gopibagh, Rajarbagh, Notun Bazar, and Mohakhali.

Residents from these areas said irregular larviciding and adult mosquito control, as well as negligence to clean waste-filled drains and canals, are undermining the effectiveness of city corporations' efforts to control mosquitoes amid the rising dengue cases in the country.

The situation outside Dhaka appears even more critical. Some city corporations face shortages of mosquito repellents, while others lack sufficient manpower, and many fail to conduct regular mosquito control supervision.

For example, in Barishal city, mosquito control activities have been largely halted since 5 August, exposing residents to mosquito-borne diseases. While in Sylhet, city corporation officials report a shortage of mosquito control chemicals, compounded by financial and manpower constraints.

Irregular, ineffective measures

Sahara Khatun, a resident of Shewrapara, Dhaka, said she rarely sees mosquito fogging in her area. "We live next to a canal and we have to endure mosquito bites even during the day. The city corporation doesn't clean the drains or remove canal waste," she said.

"Two people from the house next door contracted dengue and had to be hospitalised," she added.

Entomologists say the use of ineffective chemicals is another reason behind the government's failure to curb the mosquito population.

Even city corporation mosquito control workers admit to the ineffectiveness of their efforts. A fogging worker in the Badda area of Dhaka North, speaking to TBS on condition of anonymity, said, "We know the fog we spray doesn't work effectively, but the corporation continues to use it. Spraying only on the streets won't kill the mosquitoes – they just disperse and fly into nearby buildings."

Dr Fazle Shamsul Kabir, acting chief health officer of Dhaka South City Corporation (DSCC), emphasised the challenge of controlling mosquito breeding in clogged drains and canals, largely due to public littering.

"The DSCC continues to apply larvicides and insecticides to stagnant water and dirty areas, but challenges persist in hard-to-reach places and spaces between buildings," he explained.

Entomologist Manjur Ahmed Chowdhury criticised Bangladesh's insecticide procurement system, pointing to corruption and the use of ineffective chemicals. "The government must adopt a comprehensive cleaning and anti-mosquito programme. Without decisive action, dengue and other mosquito-borne diseases will remain an annual problem," he warned.

Experts say unlike other mosquitoes that might breed in dirty or polluted water, the Aedes mosquito, responsible for spreading dengue fever, thrives in clean, stagnant water because such environments are ideal for laying eggs and nurturing larvae. This preference makes urban areas particularly vulnerable.

Bangladesh has recorded its second-highest annual dengue death toll, with 475 fatalities and a total of 89,603 cases reported by the Directorate General of Health Services (DGHS) as of 27 November.

Last year, the country recorded 1,705 dengue-related deaths and a total of 3,21,179 dengue cases.

Mosquito control outside Dhaka

Outside Dhaka, dengue outbreaks have increased in several cities, including Barishal, Chattogram, Khulna, and Rajshahi.

Residents say mosquito control activities in Barishal city have largely stalled in recent months, particularly since 5 August.

Rebecca Begum, a resident of Ward 11 in Barishal City Corporation, expressed frustration over the worsening mosquito problem. "Mosquito infestations have become unbearable in the city. Now that there's no mayor or councillor, no one sprays mosquito repellents or cleans the area," she said.

However, city corporation officials claim that operations are proceeding as usual. Yusuf Ali, head of the sanitation department, said, "We are collecting waste in all wards at night using large trucks, and cleanliness efforts are ongoing. Wage-based workers are effectively carrying out these tasks."

Even with the onset of winter, mosquito infestations persist in Khulna city. Residents have criticised the Khulna City Corporation (KCC) for its lack of effective initiatives to control the problem.

Several families reported that they are spending between Tk200 and Tk500 per month on mosquito control measures.

Anisur Rahman, KCC's chief waste management officer, stated that to curb mosquito breeding, the city is spraying a mixture of 80% diesel and 20% furnace oil in the drains. Additionally, larvicides and adulticides are being used to control the mosquito population.

Rahman further said, "Without public cooperation, controlling mosquitoes will not be possible."

In Cumilla City Corporation, eight fogging machines are currently in operation, with plans to procure four more this week. However, officials say these machines are insufficient for the city. A shortage of equipment, inadequate funding, and a lack of manpower have made mosquito control challenging across all wards.

Russell Dostgir, a resident of the Old Chowdhuripara area in Cumilla city, complained, "The city corporation is no longer spraying insecticides as regularly as before."

Nishat Sultana, assistant director at Cumilla Medical College Hospital, noted that while the rate of dengue cases this year is lower than last year, the local-level infection rate has risen significantly.

Nazim Uddin, chief health officer of Cumilla City Corporation, said that fogging is expensive, but they are still trying to manage it.

Zubair Hossain, monitoring officer of the mosquito department at Rajshahi City Corporation, said, "We are currently focusing more on larvicide spraying for mosquito control. This activity is ongoing daily."

Meanwhile, the canals are blocked due to the ongoing waterlogging project in Chittagong City Corporation.

Due to this, mosquitoes are also increasing.

Most of the time, mosquito control workers applying adulticide (fogging) without cleaning these canals.

Sharful Islam Mahi, Mosquito Control Officer of Chittagong City Corporation told TBS that fogging is being done regularly. 

To increase the manpower, 90 trained people added to the fogging program.

Currently, about 250 people are carrying out regular fogging activities. 60-65 thousand litres of mosquito control chemicals are required annually.

Regarding fogging in the canals, he said that sometimes large canals where waste has accumulated have to be fogged immediately.

But removing the sewage from the canal is time-consuming. Therefore, fogging is done on the waste. Although there is a rule to fog after removing the waste.

Mosquito control activities halted in Sylhet

The Sylhet City Corporation officials report that they are unable to carry out mosquito control due to a shortage of insecticide. The supply of mosquito control chemicals ran out eight months ago, and the corporation is also facing financial and manpower shortages.

Zahidul Islam, chief health officer of Sylhet City Corporation, said, "For nearly a year, various issues have caused delays in mosquito control efforts. Since March, the programme has been completely halted."

"If the government does not provide funding, SCC will initiate mosquito control efforts on its own within this month," he added.

[Our correspondents Jobaer Chowdhury in Chittagong Bureau, Bulbul Habib in Rajshahi, Debashish Debu in Sylhet, Tayubur Rahman Sohel in Cumilla, Sayed Mehedi Hasan in Barishal, and Awal Sheikh in Khulna contributed to this story]

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