On April 25th of every year, the world commemorates World Malaria Day. The disease needs no introduction. The day is not meant to be a celebration of the disease but a moment to reflect on the burden it causes, efforts to eradicate it, and strategise how to continue fighting it. 

This year, I became interested in the latest tools in the arsenal for malaria control and eradication using biotechnology and genetic biocontrol. Malaria, like other vector-borne diseases, can be mitigated by targeting the parasite, plasmodium, or the vector of the parasite, mosquitoes, particularly the three species of importance in the genus Anopheles. 

Many interventions have been deployed to suppress and control the vector in several multimillion-dollar programmes, including using mosquito nets treated with long-lasting insecticide, indoor residue sprays and community-level destruction of breeding grounds using insecticides and bio-insecticides. 

Over the years, these approaches have been successful to an extent. However, malaria continues to be a preventable common cause of death, especially to children under five, especially in sub-Saharan African countries like Tanzania, with over 200 million malaria cases and 403,000 deaths in 2020.

Malaria-endemic

Tanzania is one of the leading malaria-endemic countries in the world, accounting for four per cent of all malaria deaths globally in 2021. Although overall deaths due to malaria have been decreasing in Tanzania, falling by 71 per cent between 2015 and 2021, the disease is still responsible for over 30 per cent of the national disease burden in Tanzania and, thus, a top health priority. Tanzania sees 4.4 million clinical and confirmed malaria cases annually.

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Further, over time, mosquito vectors can develop resistance to the pesticides that are supposed to kill them, so the more time we spend trying to control and eradicate them, the higher the chance of developing resistance. These challenges call for new, innovative, and practical approaches to managing and, even better, eradicating malaria.

Technologies such as genetic biocontrol can make malaria a part of history. This technology encompasses technologies that modify the genetic makeup of disease vectors, such as mosquitoes, by either “editing” or “adding” genes that reduce the fitness of the vector and its disease transmission capacity.

In the case of mosquitoes, genetic biocontrol involves genetic modification to reduce the ability of mosquitoes to reproduce, leading to population suppression and genetic modification to restrict the growth of parasites within the mosquito, leading to population modification.

When reading up about the technology, one will often come across the term gene drive. Gene drive is a genetic modification meant to increase the chances of the modified or introduced genes being inherited across populations or generations. This usually involves adding a promoter that is only active during meiosis.

Transmission Zero Project

The Transmission Zero Project aims to eradicate malaria by utilising genetic biocontrol of mosquitoes, mainly three species of Anopheles mosquitoes responsible for more than 85 per cent of transmissions in Tanzania.

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In this case, genetic modification is done by introducing genes that code for toxins against the parasites that cause malaria. Mosquitoes obtain these parasites when they feed on blood from an infected person. 

The parasites must complete at least part of their lifecycle inside the mosquito gut before they can be transferred to another host, as the mosquito feeds from other hosts. This usually takes about 1-2 weeks. Genetic modification targets this period.

Genetic modification causes mosquitoes to produce toxins that slow down the average growth of the parasite, thus reducing the chance that mature parasites will affect other hosts in subsequent mosquito meals, such as human beings. 

The toxins are magainin two from the African claw frog Xenopus laevis and melittin, a toxin component of the European honey bee Apis mellifera. In addition, the mosquito lifecycle lasts only seven to fourteen days, so only one or no complete population of the parasites can mature and be transferred to other hosts before the mosquito dies. 

Genetic modification also reduces mosquito survival fitness, slowly reducing their population and further contributing to the eventual elimination of malaria.

In Tanzania, the technology is led by researchers at the Ifakara Health Institute (IHI), including Dr Brian Tarimo, who I interviewed to understand the technology better. 

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Unfortunately, the technology is nowhere near release or deployment for several reasons. One reason is the lack of regulatory frameworks that will allow the safe adoption and regulation of the technology, which may take seven to ten more years. 

So far, the technology has yet to be deployed elsewhere, and current efforts to develop the regulatory framework take a regional approach (Africa-wise). As Dr Tarimo puts it, mosquitoes don’t need passports to cross borders. 

It will be self-defeating if one country releases the technology while its neighbours don’t. The technology would make more sense with simultaneous deployment or at least having a harmonised regulatory environment between neighbouring countries such that when genetically modified mosquitoes spread across borders, it doesn’t cause challenges.

In general, genetic engineering technologies face challenges from activists, usually religious leaders and ecological and biodiversity advocates. 

Resistance

In a recent stakeholder meeting, I participated as a researcher in African conversations on gene drives for malaria control and elimination. Most of the participants, representing diverse groups, including religious leaders, local government leaders, students, researchers, doctors, media, and the central government, were positive about the technology and shared suggestions on areas of improvement. 

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However, a few have adopted an attitude of mistrust towards GM technology, and I suspect not just for mosquitoes but in other areas, such as agriculture. The concerns aired largely ignore the science behind the technology and repeat the same scientifically impossible fears. 

One common concern is that eliminating mosquitoes leads to an ecological collapse. This ignores the fact that most current approaches also target eliminating mosquitoes in general but use insecticides, some of which may have environmental consequences and harm other non-target insects. 

Meanwhile, genetic biocontrol can either suppress or eliminate mosquitoes from a very specific genus or species of mosquitoes. Therefore, while stakeholder dialogue is critical to consider all possible concerns as the technology is developed and prior to deployment, unnecessary fear-mongering and baseless concerns actually stifle progress.

The chat with Dr Tarimo was informative and excited me about a future where malaria is no longer a challenge. In his message to the general public, he acknowledged that people don’t like change. Other technologies, such as refrigerators, cars, and even electricity, faced their fair share of rejection and criticism when they were introduced. 

Dr Tarimo understands that the technology is new and may spark doubts. Still, he believes we must do more research to learn more about it and generate scientific evidence to form the basis of acceptance or rejection. We should let science decide.

Aneth David is an academic and research scientist at the University of Dar es Salaam (UDSM). She can be reached at anethdavid367@gmail.com and on X as @anethdavidd. The opinions expressed here are the writer’s own and do not necessarily reflect those of The Chanzo. If you are interested in publishing in this space, please contact our editors at editor@thechanzo.com.