Opinionista Ivo Vegter 7 August 2018

Malaria: The ethics of deliberate extinction

Despite all our efforts, malaria remains one of the most common killers on the planet. Using genetic engineering to cause the deliberate extinction of its carrier mosquitoes is now actively being funded. The question is, should we do so, and if so, what’s next on the list of nasties to be eradicated?

Malaria kills at least 438,000 people every year, 70% of whom are children. Some estimates are significantly higher. In 2016, 216 million people were infected and suffered debilitating symptoms including fever, dizziness, vomiting, headaches and seizures.

Enter Oxitec, a genetic engineering firm that specialises in technologies to control insect populations that threaten human health and agricultural crops. Recently, the Bill & Melinda Gates Foundation funded efforts at Oxitec to develop a strain of mosquitoes that could eradicate the Anopheles gambiae mosquito, the females of which transmit the malaria parasite.

This follows earlier successes with the deployment of self-limiting strains of Aedes aegypti, which transmits Zika, dengue fever, chikungunya and yellow fever. Dubbed the Friendly Aedes, the genetically modified mosquito reduced native mosquito populations in trial areas in Brazil by 81%, relative to control areas. This reduced the incidence of dengue fever by 91%.

Upon release into the wild,” explains the company, “male-selecting strains mate with wild females, and only male offspring with a self-limiting gene survive to adulthood. The female offspring from these matings – only female mosquitoes bite – will die before reaching adulthood. The surviving non-biting males subsequently seek out and mate with more wild females and pass along the self-limiting trait for up to 10 generations before no longer persisting in the environment. When deployed as part of an integrated vector control programme, this strain is anticipated to dramatically reduce wild populations of this malaria-transmitting mosquito species, while still ensuring Oxitec self-limiting mosquitoes do not persist in the environment.”

The contamination of wild populations by GM varieties is one fear, but another is that driving an entire species to extinction could have unintended consequences for the ecosystems of which it forms part.

A new report, however, suggests that eradicating this mosquito will not substantially impact local ecosystems.

Most predators identified consume many other insect species and there is no evidence that any species preys exclusively on any anopheline mosquito.”

This makes genetically engineered extinction a far superior method of fighting malaria than traditional interventions, such as draining swamps, erecting mosquito nets or spraying insecticides, which all have limited impact and can cause collateral environmental damage.

There are other reasons, too, why engineering the extinction of parasites and disease carriers can be a justifiable approach to some diseases. Even diseases that can be well controlled with drugs or vaccines have the ability to bounce back, and often do, especially in poor countries were control programmes are patchy.

They may develop resistance to drugs, which is exactly what happened with malaria. The plasmodium parasites that cause it became resistant to the main drug that was being used against it, and the mosquitoes that carried the parasites became resistant to popular insecticides.

But isn’t species extinction bad? And if you engineer the extinction of a species deliberately, don’t you go directly to hell, without passing go?

Humanity has only been aware of species extinction for just over 200 years. The notion that humans have caused extinctions is even more recent, as is the realisation that some of those extinctions were not by accident.

With the rise of the environmental movement in the 1970s, the prevailing view of species extinction was exemplified by organisations dedicated to prevent it, such as the Worldwide Fund for Nature (WWF).

It is reflected in the notion of a Red List of species that are vulnerable to extinction, maintained and published by the International Union for the Conservation of Nature (IUCN). In it, even non-threatened species (“near-threatened”, as the IUCN calls them) are given protected status. Species that are doing just fine are also labelled negatively, as being of “least concern”.

This view holds that species conservation – or in more modern parlance, biodiversity – not only has ecological value, but has intrinsic value. Species diversity supports the genetic variety and robustness of life on Earth and helps to maintain ecosystems in stable equilibrium. To prevent species extinctions, in this view, is a matter not only of practical nature conservation, but of ethics.

While all this is true, the conservation of species became an end in itself. In a seminal paper published in 1985, entitled “What is conservation biology?”, Michael Soulé writes that the discipline “addresses the biology of species, communities or ecosystems that are perturbed, by human activities or other agents”.

He calls it a “crisis discipline”:

Its relationship to biology, particularly ecology, is analogous to that of surgery to physiology and war to political science.”

Note the focus on the human damage to the environment, without regard for the fact that humanity must control, harness and manage nature in order to flourish, and even to survive. Soulé placed emphasis on the intrinsic value of biodiversity.

More modern views on conservation recognise that ecosystem health and diversity are important both in their own right and for human welfare, but also take into account the legitimate interests of humanity in managing nature.

A paper written by Peter Kareiva and Michelle Marvier in 2012, proposes to review Soulé’s principles, defining “conservation science” as a “broader interdisciplinary field that explicitly recognises the tight coupling of social and natural systems”. (A full-text copy can be downloaded here, upon free registration.)

Today, one of the most important intellectual developments is the recognition that ecological dynamics cannot be separated from human dynamics,” they write. “Therefore, Soulé’s original delineation of conservation biology is in need of a broader framework that we label conservation science to distinguish it from an enterprise concerned solely with the welfare of nonhuman nature. Unlike conservation biology, conservation science has as a key goal the improvement of human well-being through the management of the environment.

If managing the environment to provide human health and safety were the only goal of conservation science, we would probably label it environmental science. The distinguishing feature is that in conservation science, strategies to jointly maximise benefits to people and to biodiversity are pursued; it is a discipline that requires the application of both natural and social sciences to the dynamics of coupled human-natural systems.”

The authors note that ecosystems which have been subjected to extensive modification as a result of human activity are routinely ignored by conservationists. Yet one cannot pretend the world can be returned to a pristine state. Human impact on nature is a given. The authors argue that areas impacted by human activity can still offer significant conservation value in terms of both ecosystem services and biodiversity.

The paper concludes:

Given the magnitude of human impacts and change, conservation cannot look only to the past. Instead, it must be about choosing a future for people and nature. Forward-looking conservation protects natural habitats where people live and extract resources and works with corporations to find mixes of economic and conservation activities that blend development with a concern for nature. … In summary, we are advocating conservation for people rather than from people.”

This brings us back to the idea of driving Anopheles gambiae (and any other disease-carrying mosquito species) to extinction. If this turns out to have limited or manageable environmental impact, other than the species extinction itself, it would be ethically wrong not to pursue such an approach.

In Conservation in the Anthropocene, the same authors write:

The trouble for conservation is that the data simply do not support the idea of a fragile nature at risk of collapse. Ecologists now know that the disappearance of one species does not necessarily lead to the extinction of any others, much less all others in the same ecosystem. In many circumstances, the demise of formerly abundant species can be inconsequential to ecosystem function. The American chestnut, once a dominant tree in eastern North America, has been extinguished by a foreign disease, yet the forest ecosystem is surprisingly unaffected. The passenger pigeon, once so abundant that its flocks darkened the sky, went extinct, along with countless other species from the Steller’s sea cow to the dodo, with no catastrophic or even measurable effects.”

Having established that causing extinctions deliberately in order to protect human health or welfare is ethically justifiable under certain conditions, we must ask ourselves the question, what’s next?

What about helminths, a catch-all term for numerous kinds of parasitic worm? Do they serve a useful ecosystem function that cannot be served by other organisms, or does the human suffering they cause trump environmental considerations? Eradication of such worms is already being discussed, but traditional means involving deworming pesticides are not without risk. Could genetic engineering come to the rescue and wipe these pests out for good?

Leaving aside the obvious viral and bacterial candidates, what about parasites like toxoplasmosis, giardia, bilharzia, chagas disease, or scabies mites? Who wants pubic lice, head lice, Guinea worms, chiggers or filariasis, which causes the permanently debilitating and disfiguring condition commonly known as elephantiasis?

Would the extinction of the blackfly, which transmits river blindness, or the tsetse fly, which causes sleeping sickness, the mango fly, which causes subcutaneous maggot infestation, or the sand fly, which causes Leishmaniasis, make the world a worse place?

Bed bugs don’t cause disease, but do we really need them around? What about the common flea, which spreads numerous diseases including plague?

We are all aware of species we would prefer not to go extinct. Decades of environmental propaganda has ingrained in us the fear of extinctions. With new genetic engineering techniques, however, it is possible to deliberately cause species to go extinct.

That means we need to decide which species are good candidates for being wiped out. The deaths of millions and the suffering of hundreds of millions of people can be prevented, as long as we take seriously the injunction to “jointly maximise benefits to people and to biodiversity”.

By eradicating malaria alone, we could save 11 million lives by 2040, and unlock $2 trillion in economic value, according to the Bill & Melinda Gates Foundation.

Imagine how much we can achieve if we broaden our ambitions to the destruction of the many other disease vectors, parasites and pathogens that do not play critical roles in ecosystems. Extinction could mean a new life for millions. DM

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