Experts from the International Atomic Energy Agency (IAEA) and the World Health Organization (WHO) have helped Bangladesh assess the current dengue outbreak in the country and draw up a plan to test a nuclear technique to suppress the mosquitoes spreading the disease.
At the request of the Government, the IAEA and WHO experts recently visited the capital Dhaka and met officials from the Ministry of Health and Family Welfare and the Ministry of Science and Technology to discuss the possibility of using of the Sterile Insect Technique (SIT). The SIT is a type of insect birth control that uses radiation to sterilize male insects. These are released in large numbers to mate with wild females, which then do not produce any offspring, reducing the target insect population over time.
The experts agreed with Bangladesh officials on a four-year workplan that includes the selection of a pilot site for the release of sterile male mosquitoes in 2021-22, and a schedule for IAEA technical assistance, in partnership with the Food and Agriculture Organization of the United Nations (FAO), to train national staff, upgrade existing facilities to mass rear and sterilize the insects, and collect baseline data ahead of releases.
“The SIT has been successfully implemented against numerous insect pests of agricultural importance and is now being adapted for use against mosquitoes,” said Rafael Argiles Herrero, entomologist at the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture. “The method is very specific to the target species and has no impact on other living organisms or the environment.”
A country of some 160 million people, Bangladesh is facing the worst outbreak of dengue since its first recorded epidemic in 2000. The South Asian nation has seen the number of cases rise to over 38,000 since January 2019, with the daily admission of over 1,500 new dengue patients in hospitals in recent weeks. The outbreak has also caused over 40 deaths since the beginning of the year.
Dengue is a mosquito-borne viral infection transmitted mainly by Aedes mosquitoes, which typically breed in water containers. The disease causes debilitating flu-like symptoms, and some strains of the virus can lead to potentially lethal complications.
“Bangladesh already established a mosquito insectary in 2008 under an FAO/IAEA project to conduct basic research on the application of SIT,” said Mahfuza Khan, Director and Chief Scientific Officer at the country’s Institute of Food and Radiation Biology. “The insectary can produce 30,000 to 40,000 mosquito larvae per week for SIT application, and the aim in the next four years is to increase this number and test the sterile male mosquitoes in semi-field and field conditions.”
The joint mission to Bangladesh is part of a newly established collaboration between the IAEA and WHO. The two organizations signed a Memorandum of Understanding in July 2019 to intensify research and development on the use of SIT to fight disease-transmitting mosquito vectors.
“The collaboration aims to provide more evidence on the benefits of the SIT against human diseases transmitted by mosquitoes,” said WHO expert Rajpal Yadav. “Preliminary results from field trials using sterile male mosquitoes are very encouraging, but we need more data to show reduced disease incidence before large-scale implementation can be recommended.”
Vector-borne diseases such as malaria, dengue, Zika, chikungunya, and yellow fever account for 17 per cent 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.
As part of the IAEA and WHO collaboration, a recent call was put out by the Special Programme for Research on Tropical Diseases (TDR/WHO) for public health partners to test the SIT technology against mosquitoes and carry out epidemiological evaluations. Three multi-country proposals targeting main disease-transmitting mosquito vectors Aedes aegypti and Aedes albopictus will be selected for two-year pilot projects.