Millions of transgenic mosquitoes are to be released into the fishing village of Pulau Ketam off Selangor, Malaysia, as part of an international series of field trials to fight dengue fever . The Malaysian field trials will be undertaken by the Health Ministry's Institute of Medical Research (IMR) in collaboration with Oxitec Ltd., a spin-off biotech company from the University of Oxford in the UK. This follows the reported success of confined laboratory trials conducted under the supervision of the IMR over the past year.
The technique, which has won Oxitec the Technology Pioneers 2008 award at the World Economic Forum, involves releasing transgenic male Aedes mosquitoes carrying a ‘killer' gene to mate with wild female mosquitoes, which causes (nearly) all their progeny to die. This is a variant of the Sterile Insect Technique (SIT) that has been successfully used in wiping out other insect vectors in the past , though the sterile males were created by X-irradiation, and not by transgenesis.
The release of sterile males is considered “environmentally benign” , as only female mosquitoes bite and suck blood and transmit the disease-causing virus; not the male mosquitoes.
If the Pulau Ketam trials are successful, the transgenic killer mosquitoes will be released in bigger towns which have a high incidence of dengue . Dengue is reported to be the fastest growing vector-borne disease in the world, affecting 55 percent of the global population with an estimated 100 million cases in over 100 countries. Chikungunya, a disease similar to dengue fever and also spread by the Aedes mosquito, has become a major problem, at least in India, where there were 140 000 cases in 2007.
Oxitec has received regulatory and import permits for confined evaluation in the US, France and Malaysia, while still holding discussions with regulators of other endemic countries such as India.
Environmental groups fear that releasing the transgenic mosquitoes may affect the ecosystem and cause further damage. But there has been remarkably little informed reporting on the nature of the potential hazards involved.