A massive rise in mosquito population in Dhaka has brought back the fear among its residents that this year may see a dengue outbreak even deadlier than that of the last year.

City residences are swarmed by mosquitoes day and night, even apartments in the high-rises are not spared, with mosquitoes always finding a way to enter or droning on the doorstep.

A recent study corroborates the situation, revealing that in Dhaka city and its outskirts, mosquito population has risen by 40 per cent in just two months, starting from the last week of January.

The increase in mosquitoes implies that timely action was not taken to control its growth, which, health experts and government officials said, may cause a massive dengue outbreak this year.

‘I have never seen such swarms of mosquitoes before. It increases manifold during the night,’ actor Jyotika Jyoti, a resident in the capital’s Niketan, told New Age on Friday.

Jyotika, also a ruling Awami League central sub-committee member on forest and environment affairs, observed mosquitoes to fly in different directions during fogging by the city corporation.

Jahangirnagar University zoology professor and vector management expert Kabirul Bashar led the three-member study under which traps were set up in areas, including Jatrabari, Uttara, Mirpur and Dakshinkhan in the capital, along with its outskirts, including Savar and Jahangirnagar University areas.

‘We have set up traps in 12 spots and made an average daily count based on which estimated the monthly average,’ professor Kabirul Bashar said, adding that traps were set both in and outside of residences.

In the traps they had found 99 per cent Culex mosquitoes and one per cent Aedes mosquitoes, he added, putting down the rise in Culex population to the lack of regular cleaning of the drains and canals in Dhaka.

Culex mosquito causes diseases like Japanese encephalitis, Lymphatic filariasis and West Nile fever,  according to the World Health Organisation report on Vector-borne diseases published on March 2, 2020.

Entomologists, however, said that though Culex has accounted for most of the mosquitoes in this study, it generally indicates the authorities’ failure to put in place an effective mosquito control mechanism. They feared a boom in Aedes population as soon as the season of its breeding arrives this summer with intermittent light or moderate rain.

The main dengue season starts in the middle of April.

‘Authorities clearly failed to contain Culex mosquitoes. If they act the same way, they will surely fail to control Aedes as well,’ said former IEDCR principal scientific officer Touhid Uddin Ahmed, adding that it requires a yearlong surveillance to control Aedes mosquitoes.

The study surveyed Uttara, Dakshinkhan and Mirpur areas under the Dhaka North City Corporation.

Dhaka North City mayor Atiqul Islam told New Age that the Uttara sectors 16, 17, 18, 19, 20 and 21 are under Rajuk jurisdiction, where grass and bushes in the empty plots have turned into Culex breeding grounds.

‘Rajuk is not keeping those places clean and these places are not in our jurisdiction. Rajuk should be asked why it is not keeping the areas under its jurisdiction clean,’ Atiqul added.

Asked about the mayor’s allegations, Rajuk chairman Anisur Rahman Mia said that they had already handed over the plots to its owners and the area now falls under the DNCC jurisdiction.

‘We have given letters to the DNCC for four to five times to ensure the civic facilities for the city residents in the area. We cannot kill mosquitoes and it is not our task. If we buy mosquito killing ingredients, how will we use it as we do not have expert manpower to kill mosquitoes?’ he added.

Rajuk chair Anisur, however, said that they would see what they could do about the matter.

Dhaka North City mayor also slammed the Civil Aviation Authority of Bangladesh for not containing the mosquito breeding in its grounds.

The High Court, since 2019, has ordered for several times the authorities concerned to conduct concerted anti-mosquito drives with participation of all parties, including Civil Aviation Authority of Bangladesh and Dhaka North City Corporation, in the Hazrat Shahjalal International Airport compound.

On June 8, 2022, the HC expressed dissatisfaction over the government failure to control mosquitos at the airport.

Dhaka South City Corporation chief health officer Fazle Shamsul Kabir said that he did not accept the findings of the study report as the mosquitoes under the DSCC areas are under control except the Kamrangirchar area.

‘We are working in the field and the mosquitoes are now under control. We have found some complaints only from the lowland area of Kamrangirchar. We are cleaning old Buriganga channel,’ he added.

Abu Muhammad Zakir Hussain, a former director of the Institute of Epidemiology Disease Control and Research, told New Age that the finding of 99 per cent Culex mosquitoes is slightly unbelievable.

‘The Culex usually lays eggs in dirty waters in drain and canals. It lives in the bushes,’ he said, adding that Culex mosquito mainly causes Filariasis disease.

He observed that if the study included more spots inside homes and in stagnant water, they could have found more Aedes mosquitoes.

Dengue killed 1,705 people and sent 3,21,179 people to hospitals in 2023 alone against 853 deaths and 2,44,246 hospitalisations between 2000 and 2022, according to the Directorate General of Health Services data.

At least 1,527 people were hospitalised and 20 died of the mosquito-borne viral disease this year.

Of the deaths, 14 died in January, three in February and three in half of the ongoing month March, the DGHS data showed.