Aedes mosquito density highest in Jhenaidah and Magura, IEDCR survey finds

The density of dengue-carrying Aedes mosquitoes is rising beyond Dhaka, with Jhenaidah and Magura recording the highest concentration, according to an official survey.

The Institute of Epidemiology, Disease Control and Research (IEDCR) conducted the survey in February, March, and May across several zones, including the two Dhaka city corporations, as well as city and municipal areas in Chattogram, Barishal, Rajshahi, Kushtia, Pirojpur, Patuakhali, Jhenaidah, and Magura.

Presenting the findings at a briefing in Mohakhali on Wednesday, IEDCR Director Tahmina Shirin said Aedes larvae were most prevalent in Jhenaidah and Magura among the eight surveyed districts.

In Jhenaidah, surveyors found Aedes larvae in 54 out of 270 households across nine wards, resulting in a Breteau Index (BI) of 60. In Magura, larvae were found in 150 of 270 homes surveyed, with a BI of 55.

BI measures mosquito density based on the number of positive containers per 100 houses inspected. An index above 20 is considered a serious public health risk.

Other survey results showed relatively lower indices: 5.52 in Chattogram city, 2.5 in Barishal city, and 4.79 in Rajshahi.

Among municipalities, Kushtia recorded an index of 7.87, Pirojpur 20, and Patuakhali 19.26.

“This is the first time we’re seeing such high mosquito density in those two districts,” said Tahmina. “We still don’t know exactly why it’s happening.”

She also pointed to rising dengue cases in Barguna district in Barishal division this season, attributing the trend to water storage practices necessitated by saline water.

“People store water in large containers, often uncovered or only lightly covered, which provides breeding grounds for mosquitoes. There are also numerous plastic containers lying around,” she explained.

An IEDCR team has been sent to Barguna for an outbreak investigation following an earlier survey there in February, she said.

In Dhaka, the IEDCR found Aedes larvae in 463 of 3,147 houses surveyed in February -- about 14.71 percent of households. The BI for Dhaka South City Corporation was 8.32 and 7.95 for Dhaka North.

“A total of 13 wards across the two city corporations are at particular risk, with Breteau indices exceeding 20,” said Prof Tahmina.

Public health expert Mushtuq Husain called for faster dissemination of risk information, saying delays could heighten public panic rather than prevent it.

“People need time to prepare. Just like storm warnings, early alerts for mosquito outbreaks help people act, not panic,” he said.

Director General of Health Services Md Abu Jafor emphasised the importance of cleanliness and eliminating stagnant water, saying public awareness remains critical.

“Multiple agencies, especially the local government ministry and city corporations, have responsibilities here,” he said. “But even with all those efforts, if we don’t sleep under mosquito nets, we remain at risk.”