Public health experts have warned that Bangladesh's dengue situation could worsen significantly from August as persistent monsoon rainfall creates ideal breeding conditions for Aedes mosquitoes, with infections and deaths already surging sharply in July.
The warning comes as official data shows a sharp rise in both infections and fatalities compared with the first half of the year, raising concerns that the country is entering the peak dengue season.
During the first six months of this year, 18 people died from dengue. In just the first 30 days of July, however, the death toll reached 35—almost double the number recorded during the previous six months combined.
The infection trend is equally alarming. Between January and June, Bangladesh recorded 6,104 dengue cases. In July alone, infections climbed to 9,053. According to the latest figures, the country has reported 15,153 dengue cases and 53 deaths so far this year.
Health experts say July's sharp increase signals the beginning of the annual dengue peak, which typically extends through August and September. This year, however, favorable weather conditions and the expanding distribution of Aedes mosquitoes could prolong the outbreak into October.
Persistent rainfall throughout July has left stagnant water across cities, municipalities and rural areas, creating ideal breeding sites for Aedes mosquitoes. Rooftops, under-construction buildings, flowerpots, discarded tires, drums, buckets and other open containers have all become potential sources of mosquito breeding.
Professor Kabirul Bashar, an entomologist at the Department of Zoology at Jahangirnagar University, told Dhaka Tribune: "Recent rainfall has created highly favorable breeding conditions for Aedes mosquitoes. As a result, dengue infections are likely to increase further in August. However, the number of deaths will largely depend on how quickly patients seek treatment and are admitted to hospitals."
Experts say widespread stagnant water left by monsoon rains has significantly expanded Aedes breeding sites, accelerating transmission. While Aedes mosquitoes were once believed to breed only in clean water, recent research suggests they can also reproduce in semi-polluted or contaminated water, putting many previously overlooked locations at risk.
Weather conditions have further compounded the problem. Heavy rainfall early in July, followed by rising temperatures and subsequent rain, has created an ideal environment for rapid mosquito reproduction.
The density of Aedes mosquito larvae is reportedly higher across much of the country than it was at the same time last year. Experts identify Dhaka, Chittagong and Barisal divisions as particularly vulnerable, while warning of rising infections in Cox's Bazar, Comilla, Chandpur, Gazipur, Narsingdi, Mymensingh, Manikganj, Munshiganj, Narayanganj, Khulna and Bagerhat.
Barisal Division recorded the highest number of dengue cases last year, and a similar trend is emerging this year. At the same time, Dhaka continues to account for a significant share of infections and deaths.
Dengue, once largely confined to the capital, has spread to nearly every division of the country over the past several years. Increased human mobility, rapid urbanization and the wider distribution of Aedes mosquitoes have placed district and upazila towns at growing risk.
The rapid spread outside Dhaka is also placing additional pressure on healthcare services. Many district hospitals lack specialized dengue treatment facilities and adequate diagnostic capacity, making severe cases more difficult to manage.
Another growing concern this year is the changing distribution of dengue virus serotypes. Recent surveillance indicates that the DENV-3 serotype has become increasingly dominant.
Doctors warn that people previously infected with one dengue serotype face a greater risk of developing severe dengue if they become infected with a different serotype, raising concerns that the number of critical cases could increase in the coming months.
Hospitals across the country are already admitting increasing numbers of dengue patients daily. Many arrive with high fever, severe body aches, headaches, vomiting, weakness and declining platelet counts.
Doctors say many patients initially mistake dengue for a common viral fever, delaying treatment and increasing the risk of complications. They advise anyone with a fever lasting more than three days or showing symptoms consistent with dengue to seek medical attention promptly and undergo testing without delay.
Despite significant spending on dengue control every year, experts say prevention efforts continue to fall short. In many cases, mosquito control campaigns focus on areas with relatively limited Aedes breeding, while rooftops, basements, construction sites, flowerpots, water tanks, drums and discarded containers—where stagnant water commonly accumulates—receive insufficient attention.
Experts also stress that fogging alone cannot effectively control dengue. Eliminating breeding sites and destroying mosquito larvae remain the most effective ways to reduce mosquito populations.
Professor Bashar said: "To keep the situation under control, authorities must strengthen efforts to control both larvae and adult mosquitoes simultaneously. Vector control activities must also continue consistently. Sporadic or seasonal campaigns alone cannot contain dengue."
He emphasized that preventing Aedes breeding remains the most effective defense against dengue. Water should not be allowed to remain stagnant for more than three days in or around homes, while flowerpots, air-conditioner trays, drums, buckets, discarded tires and water collected at construction sites should be cleaned regularly.
Experts also urge people not to ignore fever symptoms. Anyone developing a fever should seek medical advice promptly, stay well hydrated and undergo dengue testing if necessary. Protective measures against mosquito bites should be maintained even during the daytime, when Aedes mosquitoes are most active.
Based on current infection trends, rising fatalities, prevailing weather conditions and the expanding distribution of Aedes mosquitoes, public health experts believe August will be the most critical month of this year's dengue season. Without sustained vector control, rapid diagnosis and public participation in eliminating breeding sites, infections could rise further in September and the outbreak may continue into October.
They say dengue is no longer solely a healthcare issue but a broader public health challenge linked to urban management, environmental conditions, local government performance and public awareness. Alongside coordinated government action, active public participation will be essential to prevent the situation from deteriorating further.