Four areas of the capital are at risk of dengue infection due to the presence of Aedes mosquitoes, which are carriers of the disease.
The areas are: Lalmatia and Iqbal Road under Dhaka North City Corporation (DNCC) and Sayedabad and North Jatrabari of Dhaka South City Corporation (DSCC), revealed a survey of the Directorate General of Health Services (DGHS) published on Thursday.
National Malaria Elimination and Aedes Transmitted Disease Control Programme of the Communicable Disease Control unit of the DGHS conducted the survey from March 29 to April 7 at 70 sites of 69 wards of the two city corporations.
Among the containers with Aedes larvae, the survey found the highest percentage -- 20.22 percent -- in flooded floors of under-construction buildings, 19.10 percent in plastic drums, 11.24 percent in buckets, 7.87 percent in water tanks, 6.74 percent in the holes of water meters, 2.25 percent in flower pots and trays, 4.49 percent in plastic bottles and 3.37 percent at the bottom of elevator shafts.
The survey also found that the highest number of containers with the larvae -- 43.82 percent -- were found in high rise buildings, 34.83 percent at under-construction buildings, 15.73 at singe houses and 5.62 percent in slum areas.
Manzur Chowdhury, entomologist and former president of Zoological Society of Bangladesh, said April and the first week of May has seen rainfall on five or six occasions in the city, which is favourable for the Aedes mosquito's breeding.
However, he said the ongoing restrictions to curb the spread of Covid-19 also creates obstacles for spreading dengue. Schools and colleges are major sites for spreading the virus as the young generation are the main victims.
Similarly, the restrictions on people's movement throughout the country can be a positive.
But still there is risk of dengue and authorities will have to take necessary steps to stop its spread, Manzur said.
"It will be a very big burden for us if dengue cases start to spread as the coronavirus pandemic is going on.
"Authorities will have to take necessary steps to raise awareness so people destroy all breeding sources like abandoned pots and tyres and clean flower pots, cement tanks and drums once every week," he said.
Attention should also be paid to cleaning bus stops, hospitals, vehicles seized by police, etc. in anti-mosquito drives, he added.
Educational institutions have been closed for more than a year due to the pandemic and cleaning operations have to be done in those places to eliminate breeding sources, he suggested.
Entomologist Kabirul Bashar of Jahangirnagar University said there were no alarming findings in the DGHS survey, but there is still a risk of dengue infection.
If the two city corporations and people are conscious of destroying breeding sources, the number of Aedes mosquitoes will not be high even after rainfall, he said.
But if proper measures are not taken from now, the number of Aedes mosquitoes will increase, Bashar warned.
Awareness building will have to start from now. If it is a public place, authorities concerned will have to take steps to destroy the breeding grounds and if it is a residence, then the house owner will have to take steps to clean it, he said.
DNCC Mayor Md Atiqul Islam said they were conducting drives at different places to check Aedes mosquito larvae.
"We are also sending text messages to owners of houses identified during our combing operation last year to take necessary steps against Aedes mosquitoes," said Atique.
He said they are also taking actions to identify hotspots of Aedes mosquitoes.
Atique said there was a shortage of mosquito control supervisors and they have already managed 54 supervisors for 54 wards of DNCC, given them necessary training and they are now working at field level.
"There are two entomologists in the DNCC. We have also sought 10 entomologists from the government to conduct their operation as they play a vital role to control [the spread of] Aedes mosquito," the mayor said.
He said awareness is very important, and although they were unable to conduct awareness campaigns this year amid the pandemic they are taking steps to raise awareness through social media and other platforms.
Health official of the DSCC Mir Mustafizur Rahman said they are currently conducting an anti-Aedes mosquito drive through three mobile courts.
They were also working at the zone and ward levels to control it even during the "lockdown", he said.
DSCC Mayor Sheikh Fazle Noor Taposh held a meeting with officials concerned on Monday and gave directives to take necessary steps to control Aedes mosquitoes, the health official said.