Dengue situation could worsen this year, fear experts

Highlights:

• Bangladesh faces rising dengue cases amid ongoing measles outbreak
• Aedes mosquito larvae levels exceed dangerous thresholds across Dhaka
• Experts warn dengue infections could surpass last year's outbreak
• High-risk areas include Chattogram, Cox's Bazar, Khulna, and Barishal
• Authorities urged strengthening surveillance, cleanliness, and mosquito breeding prevention
• Hospitals nationwide preparing dengue wards ahead of peak transmission season

As Bangladesh continues to grapple with a measles outbreak, the number of dengue patients being admitted to hospitals has also started to rise. Experts warn that the dengue situation could worsen this year as Aedes mosquito larvae density has crossed risky levels in Dhaka and several other parts of the country.

They say preparations to prevent dengue need to begin immediately – particularly outside the capital.

According to the Directorate General of Health Services (DGHS), from 1 January to 21 May this year, 3,017 people were hospitalised with dengue and five people died.

Dr Khabirul Bashar, medical entomologist and professor of zoology at Jahangirnagar University, told The Business Standard that the Breteau Index (BI) for Aedes mosquitoes has exceeded 20 in several areas of Dhaka – an indication that dengue transmission may be higher this year than last year.

"We are now finding the Aedes Breteau Index above 20 in different parts of Dhaka. This suggests dengue infections could be higher this year compared with last year," he said.

The Breteau Index measures the number of water containers with mosquito larvae per 100 houses inspected. A score above 20 is considered high risk by entomologists.

Khabirul Bashar said the dengue threat is not limited to Dhaka. He warned that infections could rise in Chattogram, Cox's Bazar, Khulna, Barishal and several districts including Barguna, Pirojpur, Chandpur, Mymensingh, Manikganj, Narsingdi and Gazipur, as well as areas surrounding Dhaka.

He stressed the need for immediate preventive measures, including removing stagnant water, increasing public awareness and maintaining cleanliness.

"There can be no tolerance for stagnant water. We need extensive awareness campaigns and proper waste management," he said.

He added that conventional fogging and spraying alone are not enough to control Aedes mosquitoes. Authorities must identify breeding sources and destroy larvae, while separate control programmes are needed for Aedes and Culex mosquitoes. Community participation is also essential, he said.

DGHS data shows the highest number of dengue patients so far this year came from Barishal and Chattogram city corporation areas, followed by Dhaka. Of the five reported deaths, three were in Dhaka and the other two were reported in Rajshahi and Chattogram.

January recorded the highest number of cases this year, with 1,081 infections. Cases then declined before rising again from April. In April, 640 dengue patients were admitted to hospitals. In the first 21 days of May, 534 patients were hospitalised and one death was recorded.

Dengue was first recorded in what was then East Pakistan in the 1960s, when it became known as "Dacca fever." Bangladesh reported its first major dengue outbreak between June and October 2000 and has experienced outbreaks every year since.

All four dengue serotypes have been detected in Bangladesh. Since 2010, outbreaks have largely coincided with the rainy season from May to September and periods of higher temperatures.

The country saw a major resurgence in 2019. In 2022 and 2023, reported infections and deaths surpassed all previous records. In 2024, Bangladesh recorded 1,01,214 dengue cases and 575 deaths.

Dr Benazir Ahmed, former director of the disease control division at DGHS, told TBS that rainfall could further increase Aedes mosquito breeding, making this a critical period for surveillance.

"Now is the time for surveys. If we conduct proper surveillance and strengthen Aedes control measures now, we may be able to reduce transmission during the main dengue season in June, July and August," he said.

While mosquito-control programmes are underway in Dhaka and other major cities, he said the main concern this year is dengue outside the capital.

"There has been no effective action so far to control dengue outside Dhaka. Last year dengue spread widely beyond the capital. We need to focus on smaller municipalities and rural areas as well," he said.

He warned that just as dengue outbreaks intensified in Dhaka over time, major outbreaks outside the capital are also becoming increasingly likely.

"We will face a major dengue wave – this year or next. To keep it under control, Aedes control efforts, cleanliness, preventing water accumulation at construction sites and in old drums, and regular mosquito-control operations must continue nationwide," he added.

Professor Dr Halimur Rashid, line director of disease control at DGHS, told TBS that preparations are underway to manage the dengue situation.

"We are preparing to tackle dengue. Dengue wards and paediatric wards are being kept ready in hospitals. Regular meetings are being held on the dengue situation," he said.

This month, Dhaka Medical College Hospital set up a 20-bed field hospital for measles and dengue patients.

Health Minister Sardar Sakhawat Hossain said nationwide cleanliness drives are being carried out every Saturday to help control dengue, alongside intensified mosquito-spraying activities.

"Prevention must be prioritised over treatment. Without stronger preventive action, the dengue situation could become more complicated," he said.