At the height of one of Bangladesh’s worst dengue seasons in 2019, the country turned to the International Atomic Energy Agency (IAEA) for assistance in controlling Aedes mosquitoes, the vector of the dengue virus.
Assistance came immediately, with experts from the IAEA and the World Health Organization (WHO) helping Bangladesh draw up a plan to test a nuclear technique – the Sterile Insect Technique (SIT) – to suppress the mosquitoes spreading the disease.
The SIT is a type of insect birth control that uses radiation to sterilize male insects. These sterilized males are released into the open environment in large numbers to mate with wild females, which then do not produce any offspring, reducing the target insect population over time.
Bangladesh has since experienced worse times in the past five years, with more people getting infected and killed by mosquito-borne diseases. The good news is that scientists rearing the sterile male Aedes in insectaries have reached a stage where they can release the sterile mosquitoes into the environment and test their efficacy in suppressing the mosquito population.
One realization now biting the scientists hard is that the area they initially thought would be ideal for the deployment of sterile mosquitoes has recently been found unsuitable for SIT validation.
Engaging with DNCC for sterile mosquito deployment
Scientists at the Atomic Energy Research Establishment (AERE), who are working on the SIT program, have recently started engaging with the Dhaka North City Corporation (DNCC) authorities to explore the possibility of selecting certain areas in either Uttara or Mirpur for the deployment of sterile mosquitoes.
Headquartered in Savar, AERE is the country’s largest nuclear research center under the Bangladesh Atomic Energy Commission (BAEC), while the Vienna-based IAEA is the world's central intergovernmental forum for scientific and technical cooperation in the nuclear field.
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When will DNCC mosquito control lab begin operations?
Chittagong mayor launches research lab to combat mosquitoDr Mahfuza Khan, who heads AERE’s Institute of Food and Radiation Biology (IFRB) division, has long overseen Bangladesh’s gradual capacity building in sterile mosquito research. The IFRB Director told Dhaka Tribune that the institute initially considered the Sripur area in Dhamsona Union of Savar for sterile mosquito deployment but recently found the area had an insignificant population of Aedes aegypti and more infestation of Aedes albopictus.
In Bangladesh, Aedes aegypti is primarily responsible for spreading dengue, not Aedes albopictus mosquitoes.
Dr Mahfuza Khan said IFRB has begun engaging with DNCC about the possibility of selecting parts of Uttara or Mirpur for the test deployment of sterile mosquitoes. However, she does not want to offer any timeline at this stage as to when Bangladesh can expect its first experiment of sterile mosquito deployment.
Successes in other countries
Mosquitoes in Fort Myers, Florida, in the United States, have been found to be developing resistance to insecticides. Under a pilot project supported by the IAEA and the FAO, sterile mosquitoes are being used to curb mosquito populations there.
On Saturday, the IAEA Office of Public Information and Communication stated: "Aedes aegypti mosquito populations are particularly difficult to manage using traditional control techniques as they are diurnal mosquitoes that use cryptic breeding habitats, which makes their larvae difficult to find and remove. In addition, these mosquitoes are becoming increasingly resistant to insecticides."
The SIT pilot project, initiated in the coastal city of Fort Myers, was previously tested on Captiva Island in Florida, about 30 miles away, during a successful pilot project between 2020 and 2022. Male mosquitoes were mass-reared and sterilized before being released to mate with wild females.
At the peak of releases, approximately 400,000 sterile males were released per week on Captiva Island. The releases led to a significant reduction in the mosquito population in the first year, 2020, and complete suppression in 2021 and 2022.
However, Hurricane Ian devastated both Captiva and Sanibel islands in September 2022, making them inaccessible by car and putting an end to the pilot project. Later, the authorities decided to move the release program to a new area on the mainland. Beginning in February this year, they are releasing sterile mosquitoes in Fort Myers.
Dr Mahfuza Khan told this correspondent that many countries in Latin America have also achieved success in mosquito control by deploying sterile mosquitoes. She is hopeful that Bangladesh can do it too.
Several countries, notably Brazil, Cuba, Germany, Greece, Indonesia, Italy, Malaysia, Mauritius, Mexico, Spain, and the United States, are developing the use of SIT for mosquito control.
Capacity development
Dr Mahfuza Khan said that under the SIT program, they have so far been able to train scientific manpower, increase the rearing capacity of sterile mosquitoes through radiation technology, and received machines and equipment worth over €70,000, with equipment worth an additional €56,000 in the import pipeline.
She said that before these capacity-building initiatives, they could rear only a few thousand sterile male mosquito pupae per week, but now they are capable of producing 150,000 sterile pupae per week.
Dr Mahfuza Khan is hopeful of achieving deployment success by the end of the current SIT program timeline, which ends in December next year.
Vector-borne diseases such as malaria, dengue, Zika, chikungunya, and yellow fever account for 17% of all infectious disease deaths globally, claiming one million lives each year. In recent decades, the incidence of dengue has increased dramatically due to environmental changes, unregulated urbanization, transport and travel, and insufficient vector control methods.
