September 29, 2019 ☼ The Intersection ☼ biology ☼ technology
Given the dangers of diseases such as dengue and malaria, we should take calculated risks in trying new solutions
This is from The Intersection column that appears every other Monday in Mint.
At the best of times, public opinion on genetic technologies, like on nuclear, is mostly at the mercy of media headlines. The awesome power of these technologies causes our “fast” brains to react instinctively with fear. In most countries, only a fraction of the population is equipped to use their “slow” brains to think these issues through, not least because the underlying science is not taught at secondary school levels.
Most of the time, anything “genetically modified” does not get good press. Good scientists know this and are careful in their communications. So, it is unfathomable why researchers from one of the world’s top universities, writing in a reputed journal, would nudge readers and media professionals to go beyond the evidence. In a study of the effects of the use of genetically-engineered mosquitoes to kill the dengue-, Zika- and chikungunya-causing Aedes aegypti mosquitoes in Brazil, scientists from Yale University insinuated that field trials went wrong, “very likely resulting in a more robust population (of mosquitoes) than the pre-release population due to hybrid vigor” and that it is “unclear how this may affect disease transmission or affect other efforts to control these dangerous vectors”.
That is enough to sow fear, uncertainty and doubt in the minds of thoughtful people and create scary headlines around the world. Unfortunately, the paper offered no data at all to support the “very likely” assessment. How editors and peer reviewers of Nature Scientific Reports allowed such an unsubstantiated conclusion to be published at all is a question. The journal subsequently posted a note saying that the editors have received criticisms and will offer a response once they have been resolved.
At stake are not only the fortunes of Oxitec, the company whose genetic technology was used in Brazil, but the prospects of a promising way to control the population of mosquitoes and the growing risk they pose to human health and welfare.
Oxitec’s technology involves modifying the mosquito genome to carry a gene that creates offspring that die before reproducing. A small percentage manage to reproduce, but independent studies have verified that the population of the targeted mosquito species is drastically reduced in a few generations.
While this way to control mosquitoes appears to be effective and selective, unintended consequences are the principal concern. The course of nature is complex. We do not know what the long-term consequences might be. It is possible that the methods we use to kill mosquitoes will come back and haunt us. It is also possible that the absence of the bloodsucking Aedes mosquito might be more detrimental to other life on earth than its presence.
In the face of the mystery of nature, it may appear tempting to retreat from the science and proscribe the use of such technologies. Why take the risk at all?
In a 2016 estimate of the economic burden of dengue in India, Donald Shepard, health economist at Brandeis University, found that the direct and indirect costs of that disease alone is around $1.1 billion per year. Even this is an underestimate because it ignores broader opportunity costs. The burden imposed by malaria, a disease spread by the Anopheles mosquito, is so large that it is macroeconomically significant. In 2001, economists John Luke Gallup and Jeffrey Sachs calculated that “countries with intensive malaria grew 1.3% less per person per year, and a 10% reduction in malaria was associated with 0.3% higher growth”.
In India, cases of malaria reduced by 24% between 2016 and 2017, mainly due to gains in Odisha. That is good news, but even so, there were over 9 million reported cases that caused around 16,000 deaths in 2017. Almost everyone in India—94% of the population—remains at risk. Looking to the future, rising temperatures and changing weather patterns are likely to exacerbate malaria risks in the northern and north-eastern states, where the transmission window might extend to three more months, even while southern and western states enjoy a reprieve. In other words, states with weaker public health systems are at risk of a higher disease burden.
If a foreign country were to use nano-drones to threaten every one of our citizens and kill 16,000 Indians every year, we would almost certainly be up in arms. There’s no ethical reason to grant the mosquito a reprieve merely on it belonging to a different species. Indeed, there is a moral case for us to use every possible means to control harmful mosquito species. If genetic technology presents us with an opportunity, India must remain open to it. It is important for projects like the ongoing caged trials in Jalna, Maharashtra, to progress to the next level. India also has an interest in the continuation of trials and release of genetically-engineered mosquitoes around the world. Given the direct, real human costs of the mosquito-borne diseases, we must not be shy of carefully taking calculated risks in trying out new solutions.
There are many more The Intersection columns here
Despite the recent controversy over the results in Brazil, no one is contesting the fact that the trial was successful in reducing the Aedes mosquito population, and no negative impact was observed even after a couple of years. Even as they stay sensitive to the risks of unintended consequences, our regulators and policymakers must not lose sight of the promise of that finding.
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