Insecticides ineffective on mosquitoes: icddr,b | The Daily Star
12:00 AM, July 19, 2019 / LAST MODIFIED: 02:03 AM, July 19, 2019

Insecticides ineffective on mosquitoes: icddr,b

City corporations to monitor effectiveness of chemicals used

Amid a concerning rise in dengue cases in Dhaka, both its city corporations have decided to monitor the effectiveness of its insecticide, as the current stock was found to be ineffective in killing mosquitoes. 

Dhaka North City Corporation (DNCC) formed a 10-member technical committee -- headed by its Mayor Atiqul Islam -- on July 15 to examine the adulticide (substance to kill adult mosquitoes) they are using, said an official.

DNCC took the measure following findings of an icddr,b research, which said the insecticides sprayed by Dhaka city corporations have no effect on adult mosquitoes, as they have become resistant to permethrin (a major chemical component of the insecticide).

Other members of the DNCC committee include representatives of Communicable Disease Control (CDC) of Directorate General of Health Services (DGHS); International Centre for Diarrhoeal Disease Research (icddr,b); Plant Protection Wing of Department of Agricultural Extension; Prof Kabirul Basar of Jahangirnagar University; President of Bangladesh Crop Protection Association AK Azad and entomologist Dr Manzur Ahmed Chowdhury.

The decision came at a recent meeting with all stakeholders at DNCC Nagar Bhaban, said Mominur Rahman Mamun, chief health officer of DNCC.

At the meeting, experts suggested increasing the density of the adulticide currently in use, until new pesticide is purchased.

The icddr,b findings were presented at a meeting of the two city corporations in May.

Funded by the US Centers for Disease Control and Prevention, researchers collected egg samples of Aedes Aegypti and Culex mosquitoes between September 2017 and April 2018 from different areas of the city, and grew the mosquitoes in laboratory.

Researchers then conducted tests on the mosquitoes in line with World Health Organization rules, said an icddr,b official.

If the death rate of mosquitoes during a certain period when insecticide is used is below 90 percent, they are assumed to have gained resistance to the insecticide, he said, referring to WHO protocol.  

“We’ve observed that the death rate is very low,” he said.

For a decade, city corporation authorities have been using 0.5 percent permethrin, 0.2 percent tetramethrin and up to 0.2 percent allethrin per litre of kerosene, and applying the mix through fogging machines to kill mosquitoes.

The icddr,b researchers have suggested using malathion and deltamethrin instead of permethrin.

According to the control room of DGHS, 5,546 people were infected with dengue and five have died across the country since January 1. Majority of the cases are in Dhaka.

MM Aktaruzzaman, manager of the malaria and Aedes-transmitted diseases programme at DGHS, said they definitely have to look for an alternative pesticide.

Contacted, Dhaka South City Corporation (DSCC) Mayor Sayeed Khokon said they will arrange a meeting with Institute of Epidemiology, Disease Control and Research (IEDCR) that selects pesticides for city corporations.

“If the adulticide in use is ineffective, they will have to prescribe which pesticide DSCC should use,” he said.

Different issues like environment and health are considered when selecting a pesticide, he added.

Chief Health Officer of DSCC, Brig Gen Md Sharif Ahmed, said they purchase both the adulticide and larvicide (used to kill mosquito larva) after getting approval of Communicable Disease Control and Plant Protection Wing. If the adulticide and larvicide are ineffective, they are not approved, he said.

They did not get any formal letter from icddr,b about the findings of the study, but have already requested CDC to provide necessary suggestions on insecticide, Sharif added.

Chief Health Officer of DNCC Mominur Rahman Mamun said they have already undertaken awareness programmes like road shows and distributing leaflets etc.

DNCC is also planning to set up groups in different areas who will encourage people to destroy Aedes mosquito larva, he said, adding that they will supply kits to diagnose dengue to all healthcare centres under DNCC, so that people can be diagnosed easily and can avail necessary treatments promptly.

It will start from next week, he said.

Mominur also said they are taking steps to increase manpower through outsourcing.

DSCC Chief Health Officer Sharif said they are emphasising on building awareness through campaigning in educational institutes, NGOs and mosques.

“We have already issued letters to the heads of schools, colleges and madrasas to inform their students so that they can in turn make their families aware,” he said.

“We will form 57 committees in 57 wards of the city shortly, so that they can destroy mosquito breeding grounds at homes and generate awareness among locals.”

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