Aedes mosquito density in Dhaka triples in 4 years: DGHS

The population of Aedes mosquitoes — the vector responsible for the transmission of dengue — in Dhaka's two city corporations has almost tripled in the last four years, according to a monsoon survey report from the Directorate General of Health Services (DGHS).

The Monsoon Aedes Survey 2023 was released by the DGHS on Wednesday afternoon. 

According to the survey report, the Breteau Index (BI) was above 20 in 9 wards of Dhaka North City Corporation in the monsoon survey 2020, while it was above 20 in 30 wards in 2023. Similarly, the BI was greater than 20 in 17 wards of Dhaka South City Corporation in 2020, whereas in 2023 it was greater than 20 in 53 wards. 

The Breteau Index describes the number of positive containers per 100 houses inspected. If any area scores more than 20 on the index, entomologists term it risky. 

Conducted between 25 August and 3 September by the DGHS, the survey also recorded the presence of Aedes larvae in 23.52% of houses under Dhaka North and 18.90% of houses under Dhaka South.

According to the report, Dhaka South's Moghbazar and New Eskaton Road areas had the highest Breteau Index at 73.33 and Dhaka North's Tejgaon Industrial Area and Pallabi areas had the highest at 60.

The survey was conducted in 1,815 households in Dhaka South while 1,335 households were checked in Dhaka North.

"Dengue transmission may not decrease unless the temperature drops. I don't see any chance of it decreasing if the rain doesn't stop. Even though dengue transmission is not dependent on nature, the breeding of Aedes mosquitoes is still dependent on nature," Professor Dr Ahmedul Kabir, additional director general of the DGHS, said on the occasion.

The DGHS official added, "WHO has recommended the use of Qdenga vaccine to prevent dengue. We have sought advice from NITAG (National Immunization Technical Advisory Group) on this vaccine. We cannot make any decision about the dengue vaccine without their advice or recommendation. 

"NITAG said that it will hold a meeting soon and give a decision. If its advice comes, then the health ministry will take a decision."

Jahangirnagar University's Zoology Professor Kabirul Bashar said, "The density of Aedes mosquitoes has increased compared to the last four years. Not only the city corporation but all the organs of the local government ministry have to work together to kill mosquitoes. A national guideline is also needed to control mosquitoes."

The number of dengue cases and deaths in the first 10 months of this year has exceeded all previous records. Sixteen more dengue patients have died and 2,564 were hospitalised across the country in the 24 hours till Wednesday morning. 

With the latest figure, a total of 1,046 dengue patients have died in the country and 214,247 were admitted to hospitals this year, according to the DGHS data.