Scientists, politicians and the public have already raised alarm about the mosquitoes, which it is claimed, have been engineered to stop the spread of dengue fever.

Oxitec, an Oxfordshire based company with strong links to biotech giant Syngenta, is behind the GM mosquito programme (1).  It argues that its insects are "biologically contained" as they are programmed to die and so the usual rules for open releases of GMOs do not apply.

Incredibly this argument has been used to bypass regulations in the Cayman Islands, Brazil and Malaysia. Now Oxitec is planning more releases in Brazil and wants to add Panama, India, Singapore, Thailand, Vietnam, the Philippines, Costa Rica, Trinidad and Tobago and Florida in the United States to its portfolio (2).

Scientific defects

But scientists at the Max Planck Institute in Germany have criticised the science behind these releases. They report that there are “deficits in the scientific quality of regulatory documents and a general absence of accurate experimental descriptions available before releases start.” (3, 4)

Oxitec says it has used genetic engineering to reduce the ability of the Dengue fever carrying Aedes aegypti mosquito to reproduce. Altered males are fed an antibiotic, tetracycline, in the lab and then introduced into the wild where they mate with wild females. Their offspring need tetracycline to develop but are supposed to be unable to find it and so they die, thereby reducing the population. It is an approach which critics believe is deeply flawed (5).

Biting GM females can survive

Dr Helen Wallace from GeneWatch UK points to a confidential Oxitec document with trial data showing that 15% of the offspring of the GM mosquitoes will survive with low levels of tetracycline in the environment (6).

This is possible as the antibiotic is widely used in agriculture and is present in sewage as well as in industrially farmed chicken and other meat. Mosquitoes carrying dengue fever are known to breed in environments contaminated with sewage, including septic tanks (7).

The ecological implications of GM insects surviving and breeding are also unknown, said Dr Wallace. Even in the absence of tetracycline contamination, GM mosquitoes can survive in the laboratory at rates of around three per cent. In the field, this would translate into large numbers of survivors given that continual releases of millions of GM mosquitoes would be needed to control dengue.

Oxitec, itself, admits that as well as GM male mosquitoes, GM females may be released accidentally, and these are the biting form of the insect which passes on disease. The company has still not dealt convincingly with the medical consequences of a GM female mosquito biting people (5).

Opposition to Oxitec’s plans is emerging. In Florida, over 100,000 people have signed an online petition demanding the United States Food and Drug Administration stops attempts to release GM mosquitoes in the state (8, 9).

Most people recover from dengue

 Globally, there are an estimated 100 million cases of dengue infection a year with numbers and spread increasing.  However, most people recover after two weeks of managing their symptoms by taking paracetamol, drinking plenty of fluids and resting (10).

In some cases, dengue can develop into the potentially fatal dengue haemorrhagic fever and dengue shock syndrome.  However globally, dengue fever causes a relatively small number (estimated 20,000) of deaths annually (11).

Oxitec argues that these deaths justify its GM mosquito. But there are alternatives in the pipeline. Sanofi, a Paris based drug firm, has invested 350 million euros in a factory to make a new dengue vaccine which will be available from 2015 (12).

The GM mosquitos have not been adequately scrutinized and are, arguably, based on a flawed concept.  Overall, Oxitec’s programme represents an unregulated release of a GM organism into the environment, with no public consultation on the potential risks and no informed consent given by national or state governments.

Ultimately, the Oxitec approach might prove valuable but at the moment it looks like a “get rich quick scheme” that is running rings around a shambolic political and regulatory system.