Resistant to insecticide, mosquitoes multiply in Dhaka

Scientists and researchers 14 months ago had said that the insecticide being used against mosquitoes is ineffective. The chemicals being sprayed in Dhaka North and South City Corporation areas are not killing the mosquitoes. Despite being aware of this, the authorities are not changing the insecticide.

The health directorate has informed the city corporations that the mosquito insecticide is ineffective. Dhaka North City Corporation has said that the health directorate has not recommended any alternative and so they are simply continuing with the previous product. Even if the authorities take initiative to change the insecticides right now, it will take at least six months before they can begin using the new product.

In the meantime, the people of the city are suffering because of the mosquitoes. And with the beginning of the monsoons, there has been an alarming dengue outbreak. There have been several dengue-related deaths too.

Experts and government officials have said that the same insecticide has been used for many years against the mosquitoes in Dhaka city. Entomologist Manzur Chowdhury, speaking to Prothom Alo, said the mosquitoes have grown resistance to this particular insecticide. New insecticide is required. Or any other alternative method can be taken up.

Former president of Bangladesh Medical Association professor Rashid-e-Mahbub told Prothom Alo the government is ignoring scientific evidence that the insecticide is no longer effective. “Such negligence of public health is unpardonable,” he said.

Health workers in the city corporation areas administer the insecticide every year. Officials say they use two products, adulticide for the fully grown mosquitoes and larvacide for the larvae. Officials of the Dhaka South City Corporation said last fiscal they procured Tk 190 million worth of insecticide. Dhaka North City Corporation spent Tk 180 million for the same purpose.

Mayor of Dhaka North Md Atiqul Islam said, “We know that mosquitoes are not being killed by some of the insecticides. The insecticide will be changed. A meeting has been arranged next week in this regard with icddr,b, IEDCR and environmentalists.”

Research findings

Scientists of the International Centre for Diarrhoeal Diseases, Bangladesh have observed that the aedes mosquito that spreads dengue is not being killed by the insecticide being used. In a research carried out between December 2017 and March 2018, they noted that the aedes mosquitoes are resistant to the insecticide.

Associate scientist of the icddr,b parasitology laboratory and leader of the research team, Mohammad Shafiul Alam, told Prothom Alo, aedes mosquito eggs were collected from various areas of the city including Azimpur, Dhanmondi, Mohammedpur, Gulshan, Korail, Mirpur 1, Uttara Sector 4, Malibagh Chowdhurypara and Khilgaon. Later in the laboratory, larva and then mosquitoes were produced from these eggs. These mosquitoes were then exposed to the insecticide being used in Dhaka city. Most of the mosquitoes did not die and were not affected by the insecticide.

Three scientists of icddr,b and three of two US organisations were involved in this research. The icddr,b scientists published the results of the research on 22 May last year in presence of the relevant government officials.

The government officials did not raise any questions not did they take any initiative to change the pesticide.

What is being done

The city corporation this year continues to use the ineffective insecticide. Researchers said that the officials of the two city corporations are well aware of the inefficacy of the insecticides.

The results of two studies were presented before Dhaka South City Corporation in April this year. Present at this meeting were scientists of icddr,b, CDC (Centre for Disease Control) and the mayor of Dhaka South, Md Atiqul Islam. On 18 June, a delegation of icddr,b and a US institution called upon mayor Atiqul Islam and his colleagues.

CDC director professor Sonia Tahmina said to Prothom Alo, “We have told the Dhaka North mayor about the effectiveness of the insecticide.”

Chief health officer of Dhaka North City Corporation Mominur Rahman Mamun told Prothom Alo, “The researchers told us which insecticide was ineffective, but did not recommend any alternative. No one has taken any decision.” He said that the process to get approval for a new product was lengthy.

Professor Rashid-e-Mahbub has said that the government must take a decision for the procurement of new insecticide with no further delay. “That is what I expect as a citizen,” he said.  

This report, originally published in Prothom Alo print edition, has been rewritten in English by Ayesha Kabir