Md Golam Sharower writes on the importance of holding three surveys, before, during and after the monsoon season to assess the density of mosquitoes that cause vector-borne diseases
IN THE evolving situation, the severity of vector-borne diseases, especially mosquito-borne diseases such as dengue and chikungunya, is increasing day by day. The worst dengue situation happened in 2023. According to government estimates, the number of infected people was 321,179 and the number of dengue death was 1,705 that year. This year until August 14, the total number of dengue-infected people was 87,891 and the total number of death was 416 whereas in 2024, the total number of infected people was 8,702 and the total number of death was 71.
Now, the total number of infected people is more than three times that of 2024, which is 25,576, and the number of death is almost double, which is 104. What remains to be understood is that the spread of the Aedes mosquito, the carrier of dengue and chikungunya, could not be controlled. Their breeding grounds must be brought under control to contain the menace. For that, regular surveillance is required to identify breeding grounds. Monitoring and evaluation are required.
In Bangladesh, this surveillance work was regularly carried out by the Communicable Disease Control under the health services directorate general. A survey was conducted every year in three phases 鈥� before, during and after the monsoon season. A survey before the season gave a clear idea of the density of mosquitoes, helping the local government ministry to plan mosquito control management based on the density. Similarly, a survey during the monsoon season helped in taking appropriate measures to control the breeding grounds. In the same vein, a survey after the season to get a glimpse into the situation that could be forthcoming the next year.
In the case of mosquito control, a survey of the density of mosquito larvae and adult mosquitoes is essential. The more it is, the more effective the steps will be. But it is unfortunate a sudden closure of the funding with which the Communicable Disease Control ran the operational plan has disrupted the regular mosquito density survey.
As a result, the post-monsoon survey of 2024 has become the pre-monsoon survey of 2025. The monsoon survey in 2025 has not yet begun. There is no certainty that it will be held at all. If the monsoon survey is not conducted, the severity of dengue will become uncontrollable. While it is necessary to conduct at least three mosquito density surveys a year by three organisations to take effective steps to control mosquitoes to prevent dengue, it is not possible to conduct three surveys on time by one organisation. In such a situation, it is necessary to continue holding the survey properly. Otherwise, the mosquitoes will not stop their activities. The mosquito-borne diseases that were only centered in Dhaka have spread very quickly and easily to remote villages.
Why should a disease that is preventable take lives? No matter how many programmes are in place, the work will not be done. As the density of mosquitoes is increasing, so are the breeding grounds. The variants of mosquitoes and viruses are changing. Testing the effective ingredients of all insecticides used, application methods, training of workers, proper supervision and evaluation of the work, public awareness and involvement in destroying mosquito breeding schools, etc need to be done very well. It will not be right to show negligence towards such tasks in any way.
It is important to complete the monsoon survey work quickly in coordination with the health and local government ministries. As local government institutions will be in the dark, ordinary people will be in the dark, too. Without mapping the mosquito density, it will be difficult to properly distribute, monitor and manage the activities of the city corporations. If it is not known which areas have dense larvae and which breeding grounds are acting as a high-risk factor, there will be a lack of proper management. If this continues, the emergence and re-emergence of vector-borne diseases will take a serious turn.
All activities, including conventional insecticides or public health pesticide analysis, will come to a standstill. The health services structure will collapse. Neglected public health awareness will end. The nation will continue to suffer. People are already going through an extreme situation because of non-communicable diseases. On top of that, such a situation of vector-borne diseases is unthinkable. There is no alternative to integrated vector management.
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Dr Md Golam Sharower is a professor and head of the entomology department at the National Institute of Preventive and Social Medicine.
