Dr Kabirul Bashar is a renowned entomologist and professor in the Department of Zoology at Jahangirnagar University. He holds a PhD in mosquito studies from Kanazawa University in Japan, and has worked with organizations such as the World Health Organization (WHO), Unicef, the Global Fund, BRAC, and national programs for controlling malaria and Aedes-borne diseases, both in government and non-government sectors. In an interview with Dhaka Tribune’s Ashibul Islam Rifat, he shared his insights on this year’s dengue outbreak, how to manage the dengue situation, and the preventive measures based on previous experiences.
Dhaka Tribune: What is your opinion on this year’s dengue situation?
Dr Kabirul Bashar: In July, our research indicated that September would see a severe dengue outbreak this year. The ideal temperature for mosquito breeding is 20-35°C. If the temperature exceeds 35°C, mosquito breeding decreases. However, when it rains, mosquito breeding increases.
Our research on Aedes mosquitoes involves analyzing parameters such as mosquito density, the number of dengue patients, temperature, humidity, and rainfall to create forecasting models. Our current research suggests that the dengue situation will remain severe in October. We believe the dengue situation will remain critical throughout the year.
Dengue is primarily spread by the Aedes aegypti mosquito. Is the same mosquito responsible for dengue throughout the country?
The Aedes aegypti mosquito is the main carrier of dengue, accounting for about 95% of cases. It is often called urban or domestic mosquito. There is another carrier, Aedes albopictus (also known as the Asian tiger mosquito), responsible for about 5% of dengue cases. This mosquito is more common in rural areas with dense vegetation. Both species have black-and-white striped markings on their bodies and legs. Some make a mistake by referring to another mosquito, Armigeres, as a dengue carrier, but it has stripes only on its abdomen, not its legs, unlike Aedes mosquitoes.
It seems that the nature of dengue and the behavior of Aedes mosquitoes have changed. Could you explain this?
The Aedes aegypti mosquito is mostly found in cities, while Aedes albopictus is more common in rural areas. These two types of mosquitoes are primarily responsible for dengue. Unplanned urbanization has led to the spread of dengue.
The behavior of Aedes mosquitoes has evolved. At one point, we thought they only bred in clean water. However, five years of research have shown that they also breed in dirty water. Previously, it was believed that they only bite in the morning and evening. But from 2021 to 2024, our research in different parts of Dhaka revealed that Aedes mosquitoes bite at night as well. Our findings have been presented at various international conferences.
Dengue used to be confined to Dhaka. Why has it spread across the country?
Dengue spreads from one city to another. When a city fails to control dengue and transportation links are good, the disease spreads to other cities. Aedes mosquitoes can travel via buses, boats, and even planes. Now, every city in Bangladesh has Aedes mosquitoes, and if a dengue patient travels there, transmission begins. To prevent the spread, dengue must be controlled at its origin.
Has dengue spread nationwide because Dhaka failed to control it?
Dengue was once confined to cities, but now it has reached rural areas, largely due to unplanned urbanization. Even in villages, people are building houses, but they often neglect proper water supply and drainage systems, leading to stagnant water where Aedes mosquitoes breed. The use of packaged food has also increased in rural areas, and discarded packaging creates breeding grounds for mosquitoes. With the urban-rural divide narrowing and discarded containers becoming more common in villages, Aedes mosquito breeding has increased, and dengue is spreading.
Dengue used to be more prevalent during the rainy season. Now, we see cases throughout the year. Can you comment on this?
Dengue was once a seasonal disease, mainly occurring during the monsoon when rainwater collected in containers. However, due to unplanned urbanization and inconsistent water supply, along with increased construction during the winter, people now store water in various containers. This water provides breeding grounds for Aedes mosquitoes. In addition, water is used year-round in Bangladesh, making it an ideal environment for mosquito breeding. If water accumulates in the winter, dengue can still occur. To prevent dengue, water stagnation must be stopped. Otherwise, dengue will continue to be a problem year-round, including during the winter months of December.
What is the mosquito situation this month?
If dengue control measures continue as they are, there will be no improvement. Dengue cases in October will surpass those in September.
What is a sustainable solution to this problem?
I have proposed a sustainable solution, which I call the KB model. I firmly believe that implementing this model can control dengue. No other method can control dengue in Bangladesh. I hope that those involved in dengue control, including policymakers, will read and consider my model.
Can you briefly explain the KB model?
In the KB model, each area is divided into several blocks, with each block containing 500-1000 houses. A health worker will visit every 15 days to monitor and inform homeowners about the presence of Aedes mosquito breeding sites. If no breeding sites are found, a green sticker will be placed on the house. If breeding sites are found, a yellow sticker will be placed, and after repeated inspections, if the house still has breeding sites, a red sticker will be placed. The government will then take legal action against the homeowner. If this model is followed for a year, it will be possible to control dengue in Bangladesh, and it will not require much money to implement.
What do you think of the government's efforts to combat dengue?
Aedes mosquitoes and dengue have been familiar foes for a long time. Since 2000, people have been affected by dengue every year, but we have not seen much improvement. Those involved in dengue control claim they are working, but the public are not seeing results.
Is private initiative lacking in dengue control?
Alongside government initiatives, private and social organizations as well as individual efforts are needed to control dengue. All citizens should inspect their premises once a week to ensure there is no stagnant water. Containers with standing water should be cleaned with detergent or treated with insecticides with the help of the city corporation. By working together, the public and the government can control dengue.
Controlling mosquitoes with mosquitoes has sparked some excitement. Is this feasible? Could it open new possibilities for us?
The mosquito control method using mosquitoes has been advertised in several countries, but it may not be very successful in megacities like Dhaka. This method works best on islands or small areas, not in large cities with different environmental factors like temperature, humidity, and pollution. However, it could be tested in smaller areas.
How can the dengue mortality rate be reduced?
Compared to other countries, the dengue mortality rate is relatively high in Bangladesh. The main cause is negligence in seeking timely medical treatment. If patients seek treatment as soon as they are diagnosed, the risk of death is low. Delays in seeking treatment increase the risk. Our health complexes are well-equipped for dengue treatment, and patients should not be transferred unnecessarily. Special precautions should be taken for children and pregnant women.
What should the general public do?
Without public involvement, dengue control is impossible. The government needs to devise a plan to engage the public. People must ensure their premises do not become breeding grounds for dengue, and the government must ensure that public spaces and government institutions are also free of Aedes mosquitoes. Coordinated efforts between the public and local government institutions are essential for dengue control.
