Bangladesh may be headed into another deadly dengue season – unprepared

In 2023, Bangladesh endured one of the world’s deadliest dengue outbreaks. It is now showing early signs that it may be headed toward another punishing mosquito season.

Although dengue numbers remain relatively low by peak monsoon standards, Bangladesh has already officially recorded 2,688 infections and five deaths as of May 10, according to the Directorate General of Health Services dengue dashboard.

During the same period last year, the country had reported around 1,773 confirmed cases and three deaths, data showed.

Epidemiologists warn that the conditions that fueled previous large-scale outbreaks are once again falling into place: intermittent heavy rainfall, weak and inconsistent mosquito-control campaigns, overstretched hospitals and a population simultaneously exposed to several disease threats.

The risk is growing as Bangladesh’s healthcare system is already struggling with a deadly measles resurgence. According to the latest Health Services figures, at least 409 people have died from measles-related illness since mid-March.

This includes both laboratory-confirmed cases and deaths among children showing measles-like symptoms.

Public hospitals and pediatric wards are already under severe pressure handling the measles outbreak, raising fears that the country could soon face two concurrent public-health emergencies. The possibility of simultaneous dengue and measles outbreaks is becoming increasingly alarming, fear the healthcare experts.

Bangladesh’s recent history offers a grim warning. In 2023, dengue killed 1,705 people and infected more than 321,000, according to researchers writing in IJID Regions, making it the deadliest year on record.

The study described dengue’s annual recurrence as “a persistent threat” and noted that Dhaka, Chattogram, Khulna and Barishal bore some of the heaviest burdens. It also warned that temporary, reactive vector-control measures were helping drive mosquito resistance rather than solving the problem.

Deadly outbreak

The following years remained severe. Bangladesh’s state news agency BSS reported that dengue killed 575 people in 2024 and 413 in 2025. Those numbers are low by monsoon-season standards. But in Bangladesh, dengue outbreaks often gather force with the rains.

In September, The Daily Star reported that dengue infections were already 81% higher than the same point a year earlier, with deaths up 43%. Experts cited intermittent rain and the absence of sustained mosquito-control drives as key reasons for the surge.

Tahmina Shirin, director of Bangladesh’s Institute of Epidemiology, Disease Control and Research, said the numbers were likely to rise further unless conditions changed. Entomologist Kabirul Bashar warned that unusually heavy rain had delayed the normal peak season and pushed it later into the year.

Those warnings matter now because Bangladesh’s weather pattern this year appears ominously familiar. Pre-monsoon showers have arrived early in several areas, and stagnant water in construction sites, rooftops, drains and discarded containers creates ideal breeding grounds for Aedes aegypti, the mosquito that spreads dengue.

In Dhaka and other cities, residents routinely complain that anti-mosquito fogging is sporadic, poorly timed or ineffective. The problem has been compounded by the institutional disruption that followed the July uprising that toppled Sheikh Hasina and the sweeping administrative reshuffles that came afterward.

In many city corporations and municipal bodies, routine mosquito-control operations slowed sharply for weeks and in some places months as officials were transferred, staffing structures changed and civic agencies struggled to regain operational continuity.

Public-health specialists and local government observers say vector-control programmes suffered from a combination of manpower shortages, procurement delays and uncertainty over budgets and chain of command.

In several urban areas, regular larvicide spraying, drain inspections and neighborhood cleanup drives either became irregular or stalled altogether. Waste management schedules were also disrupted in parts of Dhaka and other densely populated cities, worsening conditions for mosquito breeding during intermittent rains.

The interruption may prove costly because dengue prevention depends heavily on continuity. Mosquito-control campaigns are most effective when conducted consistently before and during the early monsoon period.

Even short gaps can allow mosquito populations to rebound rapidly in crowded urban environments where standing water accumulates easily. Experts warn that once transmission accelerates, authorities are often forced into reactive emergency measures that are far less effective than sustained prevention.

Why did dengue become fatal?

Dengue is not merely a nuisance disease marked by fever and body pain. Severe infections can trigger plasma leakage, internal bleeding, shock and organ failure. Bangladesh’s doctors have also repeatedly warned about the risks of secondary infection, when someone infected once contracts a different dengue serotype later.

That second encounter can be deadlier.

In last year’s reporting, clinicians said many severe cases involved secondary infections and delayed hospital admission. They also pointed to the continued circulation of DENV-2, a strain linked to more serious outcomes in previous outbreaks.

Now measles is adding pressure to the system. Measles outbreaks often expose gaps in immunisation coverage and place new demands on pediatric wards and surveillance systems.

If dengue accelerates during the rainy season, hospitals could face a dual burden: children with measles and adults and children alike with mosquito-borne fever.

That prospect raises an increasingly urgent question: should Bangladesh move beyond fogging machines and awareness campaigns and begin planning for dengue vaccination?

India, Bangladesh’s giant neighbor and frequent epidemiological mirror, has already taken a notable step. According to The Times of India, India has approved its first dengue vaccine after years of growing case numbers, which exceeded 230,000 annually in both 2023 and 2024.

The vaccine drawing the most attention in South Asia is widely understood to be based on the TV003/TV005 platform, a tetravalent live-attenuated candidate designed to protect against all four dengue serotypes. That matters because immunity to only one serotype can leave people vulnerable to more severe disease from another.

Researchers reviewing global vaccine development in Virologica Sinica described TV003/TV005 among the most promising candidates now in clinical development. They also noted that only two dengue vaccines – Dengvaxia and Qdenga – have so far received licenses internationally.

Dengvaxia, the first licensed dengue vaccine, became controversial because it posed risks for some recipients who had never previously been infected. It is now generally recommended only in specific settings and populations.

Qdenga, developed later, has been authorised in a number of countries and has shown broader usefulness, though policy recommendations vary.

The central challenge in dengue vaccination is scientific as much as logistical. A vaccine must generate balanced protection against all four dengue serotypes while avoiding antibody-dependent enhancement, an immune phenomenon that can worsen illness after later infection. Experts say that is precisely the reason why governments across the world have moved cautiously.

What should Bangladesh do?

So, should Bangladesh adopt mass vaccination immediately if that is available? “Probably not nationwide, not yet,” said Dr ANM Nuruzzaman, a public health expert. “But it should move quickly toward a phased strategy.”

Bangladesh needs robust sero-surveillance – testing populations to determine prior exposure and which serotypes are circulating. Public-health experts like Nuruzzaman have repeatedly lamented the lack of such data. Without it, he said, officials are making “policy in the dark”.

He said the government should prepare regulatory pathways to evaluate vaccines already approved elsewhere, particularly those with evidence in tropical, high-burden settings.

“Bangladesh should consider targeted vaccination in the highest-risk districts and urban centers rather than a blanket national campaign from day one,” said Nuruzzaman.

However, vaccines are not substitutes for basic governance. Bangladesh’s dengue problem has long been amplified by failures that are less glamorous than biotechnology.

Entomologist Kabirul Bashar said the country’s dengue management (or the lack of it) is defined by unmanaged waste, clogged drainage, haphazard urbanization, weak local coordination and emergency-only responses after cases surge.

No injection can compensate for neighborhoods where water pools for weeks and mosquito eggs survive dry spells, Bashar said.

Still, said Bashar, relying only on old methods is becoming “harder to justify”. Climate change is extending mosquito seasons. Urban growth is accelerating. Cross-border movement is constant. And dengue is no longer an occasional scare; it is becoming structurally embedded in Bangladesh’s public-health landscape, he pointed out.

Bangladesh learned in 2023 how lethal complacency can be. If the rains intensify and mosquito control remains lackluster, the country may relearn that lesson this year – while also battling measles, warned Bashar.

Faisal Mahmud is a Dhaka-based journalist.