The Kolkata model and cleanliness fight needed for the war against dengue

As the scourge of dengue spreads throughout Bangladesh, which has already recorded the highest number of hospitalisations in a 24-hour period ending Sunday morning, perhaps a solution lies some 300 kilometres away from the capital in India's Kolkata. 

India has seen an increase in dengue by 1,312% since the first major outbreak in 1996. 

In 2022, of the 2.3 lakh cases dengue cases, the highest of 67,271 was in West Bengal, with one of the worst-affected being Kolkata.

The respite it had enjoyed from the disease during the Covid-19 years of 2020 and 2021 came to a grinding halt.   

This year, the authorities in Kolkata have thrown down the gauntlet as case numbers have again started to rise. 

Kolkata recorded 157 dengue cases, 40 a week, throughout the month of June, without any critical cases.

Bangladesh on the other hand saw 32 dengue deaths in 25 days of June, according to the Directorate General of Health Services (DGHS). By July, the number of deaths had reached 120. A total of 30,685 people have been affected by dengue since January this year, with 18,885 in Dhaka alone.

In terms of population, Dhaka has around 2.24 crore people and Kolkata is close behind with 1.52cr. Even accounting for the population difference, the difference in the number of dengue cases is worrying.

In the mean time, Bangladesh is also coming up with its own plans.  

Just today (24 July),  the Dhaka North City Corporation announced a plan to stage a renewed assault on the mosquito menace, earmarking Tk121.84 crore or about 2.32% of its total budget on mosquito control in the new financial year 2023-24.

Under the new allocation, Tk45 crore will be used to purchase pesticides, Tk30 crore on mosquito control activities through outsourcing and Tk30 crore for the purchase of mosquito control equipment.

Government agencies have started various activities to control dengue, including spraying medicine. Photo: Mumit M

In addition, Tk7.34 crore is to be spent on cleanliness efforts and awareness building for dengue control.

But more than anything, it is the cleanliness efforts, alongside an organised campaign, which should bear the most fruit. 

This is when we turn towards the Kolkata model. 

Two days ago, in response to calls from residents to conduct fogging in their areas, Debashis Sen, chairman  of the New Town Kolkata Development Authority (NKDA), said, "Recent government statistics show that fogging does not kill mosquitoes. We need to make people aware of this."

At a meeting convened by the New Town authorities on Saturday, Sen said waste-management was the biggest issue in tackling the dengue menace, according to a report by the Telegraph India.

"Segregation of waste into dry and wet waste as per different dustbins provided by the authorities is a must. It is important that this differentiation is done at the source," he said. 

At the same time, he also highlighted the significance of conducting awareness campaigns. 

TBS file photo

The NKDA authorities also appealed to residents to deposit all kinds of scrap materials — broken plastic articles, bottles, cups and cans — to the NKDA solid waste management team as the authorities are starting a special cleanliness drive in the township to prevent vector-borne diseases.

"Scraps such as broken cups and plates are ideal places for water to accumulate where mosquitoes can breed. We are appealing to residents to deposit all such scrap materials to the NKDA solid waste management team when they collect household garbage," an official told the Times of India.

The NKDA authorities have also engaged newly formed block supervisors to conduct door-to-door surveys to know if any resident had fever with dengue or malaria symptoms.

Both the Dhaka mayors have on occasions appealed to residents to keep their surroundings clean. 

Anti-dengue drives have also been conducted and numerous people have been fined. But these initiatives do not appear to have made a dent to the dengue threat. 

And that's where Bangladesh needs to reimagine its policies and focus more on cleanliness.

The decisive data

If there is any doubt about the need for cleanliness to curb the mosquito menace, there exists data that is hard to refute. 

On Sunday (23 July), the Directorate General of Health Services (DGHS) declared eleven areas of Dhaka as "red zones", owing to the number of hospitalised patients in those localities.

Of the areas, six are in Dhaka South City Corporation and the remaining five are in Dhaka North City Corporation.

A worker of Dhaka South City Corporation sprays mosquito repellent on an open ditch at Shyampur in Old Dhaka. The photo was taken recently. Photo: Mumit M

The Dhaka South areas are – Jatrabari, Mugda, Kodomtoli, Jurain, Dhanmondi and Basabo. 

The remaining five areas in the Dhaka North are – Uttara, Mohammadpur, Mirpur, Tejgaon and Badda.

Most of these areas can be considered to be relatively unclean, not due to the lack of city cleaners, who can be seen working hard early in the morning and even in the middle of the night. 

The lack of cleanliness also arises from the presence of water bodies and ongoing construction.

In fact, construction is a major cause for concern. 

This warning had been given earlier in 2019 during a visit by Senior Entomologist of WHO Southeast Asia Region Dr BN Nagpal.

Addressing a special briefing at the office of the DGHS, he said, "Aedes mosquitoes breed in clean water. Construction projects are big sources of Aedes mosquito larvae. Caution should be taken so that water does not stagnate in construction projects."

But oftentimes, water is sprayed in under construction projects as a method of dust control.

The water then pools together and becomes a breeding ground for dengue spreading mosquitoes. 

Currently, Dhaka is going through a massive transformation, owing to a number of under construction mega projects. It needs to be checked that these don't become breeding grounds for dengue.

Fogging, while visible to residents, should not be the sole remedy against mosquitoes but one of the many.

TBS file photo of drive against dengue

During a speech by Kolkata Municipal Corporation (KMC) Mayor Firhad Hakim at the same DGHS event, he said, "Spraying insecticides will only cause mosquitoes to move to another location. A search and destroy operation must be launched in every ward of Dhaka to wipe out the Aedes mosquito population."

But top wipe out, what is also urgently needed is vector control. 

Control, not only cure 

The issue of vector control has already been brought to the government's attention. 

The government has chalked out an ambitious Tk1,288 crore project to control mosquito population and create a dengue outbreak prediction model.
The project will be implemented in the Dhaka South City Corporation, the Dhaka North City Corporation and its adjacent two municipalities - Savar and Tarabo - as well as in the Chattogram City Corporation (CCC).

According to the Development Project Proposal of the project, the Local Government Division will set up an Integrated Vector Management Unit (IVMU)  at the Dhaka Mosquito Control Office and establish one central Biological (entomology) Lab for identifying Aedes mosquitoes – carriers of the dengue virus.

The IVMU is a decision-making body working for the management of vector populations, so as to reduce or interrupt transmission of vector-borne diseases including dengue and chikungunya. The unit typically includes entomologists, epidemiologists, public health experts, and community engagement specialists.
Dr Kabirul Bashar, professor of zoology at Jahangirnagar University, told The Business Standard that integrated vector management is a commendable step for mosquito control.

"We have been recommending such initiatives for a long time to tackle not only dengue but also other mosquito-borne diseases. The success of this project will be greatly enhanced if it is spearheaded by individuals with expertise in mosquito control," he said.

More layers to the fight

Revisiting the Kolkata model, what is clear is the number of layers the authorities have made to ensure work is being done at each step. 

The city corporation monitors accumulation of stagnant water throughout the year and follows up on hospital records.

The fight doesn't only begin during monsoon. It starts before the first whispers of war have even been mutely heard.

It's all about preparation.

The Kolkata model also includes some 20-15 men, divided into two groups, working in each of the city's 144 wards, with one focused on awareness campaigns and the other on the presence of stagnant water.

Dengue outbreaks also prompt the teams to break up dengue nests as soon as possible. 

At the same time, efforts are made to reduce dengue breeding grounds, with a sharp focus on cleanliness. 

The model, the warning and failures all exist. It's time to take heed and prepare before more avoidable deaths hang over us.