Dengue spreading. Are city corporations' anti-mosquito drives effective?

Despite numerous efforts and substantial budgets allocated over the past decade, Dhaka's two city corporations have been unable to effectively control the dengue outbreak, experts say. 

The cities continue to grapple with a surge in cases, raising concerns about the adequacy of existing control measures.

To control Aedes larvae, guppy fish were released into drains, Bti tablets were applied in water bodies, and ducks and frogs were released into ponds and ditches. Additionally, drones were used to identify mosquito breeding sources. 

Conventional methods like fogging are used to kill flying mosquitoes, and larvicide spraying is done to destroy larvae. Over the past two years, both city corporations have stirred public attention by imposing fines when Aedes mosquito larvae were found in anyone's home.

Despite all these efforts, the two city corporations have not been able to adopt any modern methods, experts say. The ongoing mosquito control measures are not based on scientific methods, making it difficult to effectively eliminate mosquitoes despite these initiatives, they say.

Current anti-mosquito efforts termed ineffective

For a long time, GM Saifur Rahman, an entomologist and faculty member at the National University, has been conducting research on Aedes mosquitoes.

He told TBS, "We first need to find out why dengue spread from Dhaka to the rest of the country. The root cause lies in the methodological flaws in our Aedes mosquito control efforts. 

"Dengue-carrying Aedes mosquitoes must be controlled using the Integrated Vector Management approach. For this, a separate organisation or body needs to be established, one that will conduct year-round research on dengue and determine what measures should be taken in which areas." 

He added, "The current mosquito control efforts are like leaving it in the hands of the blind—attempts are being made without any proper research."

There is a significant lack of interest from the government in controlling dengue, Saifur said. "Even the interim government could not address the core issues. They are following the same outdated methods. There is no clear data on which areas have a higher concentration of Aedes mosquitoes or where more patients are coming from." 

The insecticide spraying and fogging being done in the mornings and evenings are not being carried out properly, he said. If there were centralised data indicating which areas are most affected, more focus could have been placed on those regions, Saifur said.

"Given how widely dengue has now spread across the country, it is impossible to control it with the current efforts," he said.

Ex-president of the Bangladesh Zoological Society Entomologist Manjur A Chowdhury told TBS, "There is no field-level survey to assess whether the dengue control efforts are effective. According to our research, less than 10% of mosquitoes are killed after fogging. Similarly, after applying larvicides, over 30% of mosquitoes in most drains remain unaffected." 

Entomologists have repeatedly emphasised controlling mosquitoes through vector management, but neither the city corporations nor the local government have implemented it, he said.

"The type of mosquitoes is constantly changing, and the rest of the world is controlling them through scientific methods, but our country has failed. We can learn from how our neighbouring city Kolkata has brought dengue under control, but those practices are not being applied here," said Manjur.

Citing examples from different countries, he said, "In Kolkata, regular monitoring is conducted in every ward, and based on the mosquito levels in specific areas, combing operations and other measures, including assigning responsibilities to locals, are taken. Additionally, in Singapore, a type of trap is used that allows people to identify whether there are Aedes mosquitoes in their homes or surrounding areas." 

If these traps are brought to the country and sold, people will willingly buy and use them for their own protection, Manjur said.

He stated that there is no regular testing to verify whether the insecticides being used by the city corporations are appropriate.

Dengue claims 8 more

According to the Directorate General of Health Services (DGHS) Control Room, 44,764 dengue patients were admitted to various hospitals across the country from 1 January to 15 October, and 223 of them have died.

As of yesterday morning, in 24 hours, the number of dengue hospitalisation was 1,108 cases with 8 new deaths. Of the 8 deaths, 3 were from outside Dhaka. Of the total deaths, 118 are in Dhaka South City Corporation and 32 in the Dhaka North City Corporation. 

Chattogram division's total cases are 8,527 and deaths are 23 while Barishal division's total cases are 3,884 and deaths are 26.

Among the districts, Cox's Bazar has the highest number of cases with 3,635, followed by Narsingdi with 1,303 cases, Chattogram with 1,174, and Barguna with 1,093 cases.

In terms of fatalities, the highest number of deaths occurred at Dhaka Medical College Hospital with 44 deaths, followed by Mugda Medical College and Hospital with 28, Mitford Hospital with 18, and Chattogram Medical College Hospital with 15.

What do city corporation officials say?

The two city corporations of Dhaka claim the number of Aedes mosquitoes increased as mosquito control workers could not carry out their duties during the student-led protests in July.

Dhaka South Chief Health Officer Dr Fazle Shamsul Kabir told TBS, "I do not agree with the notion that dengue patients are spreading from Dhaka. The daily lists provided by the Department of Health present misleading information to the nation as patients from the southern city hospitals are counted as southern patients. Last year, we used to receive concentrated cases from certain areas, but this year that is not the case."

He further said, "We are carrying out activities based on the recommendations of our own insecticide committee and the committee provided by the ministry. We are implementing a crash programme in the areas where we are seeing a higher number of patients. I hope that in the next 7 to 15 days, the number of dengue patients in the south will decrease."

Dhaka North City Deputy Chief Health Officer Rubayet Ismat Ovik told TBS that Bti will be applied soon and will reduce the Aedes mosquito population. "In July, our activities were hindered for a few days, which led to a significant increase in dengue because that was an ideal environment for the proliferation of Aedes mosquitoes."

Stating that there is still a lack of awareness among people, he said, "We are finding a high number of Aedes larvae in the basements of buildings in upscale areas. Out of 15 houses in Baridhara, we have found larvae in 10. The public needs to be more aware of this issue."