GM mosquitoes to fight dengue

New technology on the anvil

The scientists at Oxford University and its offshoot company Oxitec have come up with a new technology whereby genetically-modified male Aedes mosquitoes are released to mate with female mosquitoes of the species, and the resulting larvae are destined to perish without becoming adults. It is hoped sustained releases of the mosquitoes could suppress the population of biting female mosquitoes below the level at which they cannot spread diseases.

“Only male mosquitoes are used in the technology and since these cannot bite, the technology will not result in biting nuisance or increased transmission of any disease. It is environment-friendly, because Aedes aegypti will only mate with its own species,” S S Vasan, Oxitec’s Head of Public Health, said.

After two years of review and inspections, India’s Review Committee on Genetic Manipulation (RCGM) under the Department of Biotechnology has given permission to the International Institute of Biotechnology and Toxicology (IIBAT), Chennai, to import eggs of these mosquitoes to conduct tests under containment. The RCGM has also appointed a five-member sub-committee of government experts to oversee the experiments. “Our attempt is to experiment and evaluate a new tool available to us,” Brij Kishore Tyagi, one of the experts in the Monitoring and Evaluation Committee said.

A recent survey by the Indian Institute of Management-Ahmedabad (IIMA) had concluded that the diseases led to a burden of Rs 380 crore on Gujarat and Rs 6,120 crore on the country. Dileep Mavalankar, Chairman of IIMA’s Centre for Management of Health Services, said the new technology looked promising.

“In our study on dengue and chikungunya, we have estimated their burden on the country and state and it’s huge, so if new technology is available, it should be tried for prevention,” Mavalankar said. Aedes mosquitoes breed in clear, stagnant water, and their eggs can be dormant for even a year. So getting rid of all the breeding sites may be desirable but not practical.

According to experts, fogging with insecticides has been shown to be of limited effectiveness, and their overuse could lead to resistance and residues in the environment. Therefore new methods such as GM mosquitoes are needed, because there is no specific medicine or vaccine for chikungunya as well as for the four serotypes of dengue. A safe vaccine may take another ten years before it is available for widespread use.