Dengue on rise as Dhaka’s mosquito control drive works little

Highlights:

• 24% of mosquito-control budget remains unused in five financial years in Dhaka city
• DNCC has spent about 88% and DSCC has spent about 62% this year
• In the financial year 2021-22, DNCC allocation increased by about Tk30 crore, DSCC allocation decreased by Tk15 crore.
• Experts say insecticide causing pollution 
• Dhaka mayors insist mosquitoes under control 

With dengue accounting for 18,550 infections and 68 deaths already this year, the city corporations' anti-mosquito drives seem not to be working.

For the entirety of 2018, the number of people affected by dengue was 10,148, rising to 1,01,354 in 2019 and falling to 1,405 again in 2020.

Experts explain this drastic rise and fall in dengue cases, by saying that once dengue enters a country, it becomes hard to control if not done so initially. Infection rates rise one year and fall the next, but if it is not initially controlled, then it spreads rapidly.

This year, the number of infections is rising amid increasing allocation for fighting mosquito-borne diseases. Dhaka city authorities have stuck to fogging and spraying larvicide although these approaches have not proven to be effective in mosquito control.

Experts are now saying that it is time to adopt alternative methods and other mosquito-fighting models.

Keeping canals clean, removing weeds from water banks, installing mosquito magnetic traps at construction sites and public spaces, releasing guppy fish in mosquito-prone waters are among some steps being tried by cities around the globe, including Kolkata in neighbouring India.

Advised by entomologists, cities are shifting away from using insecticides and adopting a "green drive" to protect the environment and public health.

In cities like Florida and Singapore, genetically modified mosquitoes are being released to combat Aedes and other species causing dengue and Zika.

Dhaka, meanwhile, has not thought beyond emphasizing anything other than increasing insecticide fogging and routine drives. A breakdown of the budget allocations for mosquito control drives of Dhaka's two city corporations shows exactly this.

In the financial year 2021-22, Tk110 crore has been allocated for Dhaka North City Corporation (DNCC), of which Tk45 crore has been allocated for the purchase of pesticides, Tk3.50 crore for clearing weeds and hyacinths, Tk3 crore for implementation of mosquito control programs, Tk27 crore for outsourcing (hiring beyond city corporation employees in mosquito control activities) and Tk4 crore for combing operations. The DNCC has also allocated Tk25 crore for the purchase of mosquito control equipment.

Meanwhile, Tk35.30 crore has been allocated for DSCC. Of this, Tk22.50 crore has been allocated for the purchase of pesticides, Tk5 lakh for clearing weeds and hyacinths and Tk3.75 crore for transporting mosquito repellents. The DSCC has also allocated Tk9 crore for the purchase of mosquito control equipment.

But evidently, all these alone are not enough.

The city corporations have also held combing operations and imposed fines through mobile courts. The number of infections, however, have not been curtailed.

Entomologists, time and again, have pointed out that the only method to control the dengue population is through vector management.

A vector management method is one where prevention is prioritised, but different approaches are taken to do so including habitat control, reducing contact and chemical control, among others.

Highlighting the importance of vector management, Entomologist Manjur Ahmed Chowdhury said a proper survey needs to be conducted to find out where adult mosquitoes are most prevalent. Then, according to the identified locations, a larvicide spraying programme needs to be implemented and the community needs to be engaged to ensure they keep their surroundings clean.

Manjur suggested that involving other stakeholders, along with the city corporations, was the way forward.

"Our city corporations' lack of efforts at the start of the year has resulted in this situation. Doing anything now will not help the situation much," he said.

The Center for Governance Studies (CGS) chairman Manjur Ahmed told TBS, "We don't even need all the money allocated for mosquito control. Proper and timely application of pesticides, larvicide, and fogging would make mosquito control easier. But we lack entomologists as well as effective measures."

The two mayors, however, remain adamant that their methods are working.

"Our number of patients was below 25 on Tuesday," DSCC Mayor Sheikh Fazle Noor Taposh said at a function on Wednesday. "For the last five days, I have received 20 patients every day in Dhaka South City Corporation area, so dengue is under control in the south," he said.

Last week, DNCC Mayor Atiqul Islam, said letters were being issued to about 1,800 different individuals and organisations to take necessary steps to curb the spread of Aedes mosquitoes. A guideline has also been developed for supervisors and mosquito eradication workers, adding that mosquito control workers are working day and night.

Increased budgets, no tangible results

With the increase in the number of Aedes mosquito infections in the capital Dhaka, the budget allocation for mosquito control has also increased.

But every year during the monsoon season, the life of the city dwellers is disrupted by the bites of Aedes mosquitoes.

In the last five years, the two city corporations of Dhaka have spent around Tk292.7 crore to fight mosquitoes.

During that period, the allocation of DNCC for mosquito control has increased by about 36%, while for the more-prone DSCC it increased by only 16%.

More importantly, while the allocation has increased, the two corporations have not been able to fully utilise the funds.

For instance, the allocation for mosquito control in 2020-21 for DSCC was around Tk51 crore, but only Tk20 crore was spent.

DNCC was allocated Tk80.5 crore, while it spent Tk55.5 crore.

The other models

In 2019, when dengue cases were on the rise in Dhaka, the DNCC mayor sought to learn the experience of Kolkata in mosquito control. In a video conference with his Kolkata counterpart Atin Ghosh, he was informed that the Indian city had not used pesticides in the "last nine years".

"We're controlling mosquitoes through applying environmental and biological techniques," Atin said, suggesting that their "three-tier monitoring system" would also work for Dhaka as well.

Aedes mosquito cannot be controlled by fogging larvicide and adulticide, which can only kill culex mosquitoes, the Kolkata acting mayor told the DNCC mayor.

Earlier this year, Kolkata Municipal Corporation installed magnetic nets in the city's New Town area, showing another way of controlling mosquitoes.

Singapore, meanwhile, fought its worst dengue outbreak last year using lab-grown mosquitoes carrying a bacteria which prevented eggs from hatching and thus lowering the mosquito population.

In May this year, a Bill Gates-funded biotech firm released genetically modified mosquitoes in the Florida Keys to combat insect-borne diseases like dengue fever and the Zika virus.