Pioneering study examines potential risks of using gene drive mosquitoes to control malaria in Africa

By Mark Lynas

May 4, 2021

The non-profit research group Target Malaria has published a first-of-its-kind study of the potential risks of releasing gene drive transgenic mosquitoes aimed at combating the transmission of malaria in Africa.

Gene drive is a method of using new gene editing techniques to bias the inheritance characteristics of a target species’ offspring. In mosquitoes the aim would be to spread sterility in the population, leading to a reduction in mosquito numbers and the suppression of malaria transmission.

However, the potential power of gene drive technology has also sparked fears about possible unintended consequences. The new Target Malaria paper takes a “problem formulation” approach to evaluate and assess 46 different plausible risks that might arise to human health or the environment via the release of gene drive transgenic mosquitoes.

According to the researchers, the exercise revealed that in many cases the more the mosquito population is reduced by gene drive mosquitoes, the less likely potential harms are to be realized. In addition, the most common potential harms that were identified involved increased human or animal disease transmission.

The paper envisages the release of gene drive-carrying transgenic individuals of the malaria vector species Anopheles gambiae, one of the main disease-carrying mosquitoes in West Africa. The World Health Organization estimates that in 2019 there were 229 million cases of malaria globally, accounting for 409,000 deaths. WHO also states that 94 percent of malaria cases took place in the African region.

If gene drive transgenic mosquitoes were released in Africa, it is hypothesized that the resulting suppression of wild mosquito populations would reduce the transmission of malaria and save many human lives. These efforts are particularly important given that conventional control methods using insecticides and anti-malarial drugs are becoming less effective due to the evolution of resistance in mosquitoes.

In 2018 researchers at Imperial College in London published a report in the journal Nature Biotechnology showing that the team’s gene drive technology was 100 percent effective in suppressing populations of Anopheles gambiae in a caged experiment. Target Malaria’s paper is intended to begin the “environmental research assessment” process that must be completed before any transgenic mosquitoes are released into the wider environment in malaria-affected areas.

The paper, published in Malaria Journal, is entitled: “Systematic identification of plausible pathways to potential harm via problem formulation for investigational releases of a population suppression gene drive to control the human malaria vector Anopheles gambiae in West Africa.”

The analysis draws upon publications from a series of four regional workshops held in Africa, as well as another in the United States, between 2016 and 2019, organized by the New Partnership for Africa’s Development of the African Union Development Agency (AUDA-NEPAD) and by the Foundation for the National Institutes of Health (FNIH).  It was further complemented by extensive literature assessment, and ongoing dialogue with numerous scientific, risk and regulatory experts.

“To our knowledge, our paper represents the first systemic and comprehensive identification of the potential harms that gene drive mosquitoes could have on the environment and on human health, should they be released,” Dr. John Connolly, regulatory science officer at Target Malaria wrote.

“We hope that it will also stimulate further, broader engagement on the use of population suppression gene drive to control malaria vectors in Africa. With half a million deaths caused by malaria every year, new tools are sorely needed.”

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