Mosquitoes in Sao Tome, Principe & the New York Times
I really don’t have much to add to this excellent article on mosquitoes in Sao Tome and Principe. It includes an explanation of how to make mosquitoes resistant to malaria and maybe eliminate malaria at very low cost. The a non explanation of why this isn’t being done (there is no law against it but it appears that In Sao Tome & Principe as well as Germany everything is forbidden if it isn’t specifically allowed — and the parliament is too busy (making excuses) to decide whether to allow the effort.
I know that releasing genetically modified organisms is a very scary break with business as usual. ALso that genetic drive makes it scarier. But I note that no one has managed to think of a possible undesireable effect of the release of the genetically modified mosquitoes. Critics of the proposal are quoted in the article, but there ciriticisms have nothing to do with possible consequences of actions. Nothing. Zero. Niente.
Other articles in that days Times note the hundreds of thousands of malaria deaths per year and the fact that “Mosquitoes are a Growing Threat”. Notice both that the status quo is unacceptably bad *and* we can’t just choose it, because things are changing whether we change policy or not.
I link to them, because I care a lot about genetic engineering of mosquitoes and also because this is one of a series of posts starting with “Is Choosing the Status Quo sage ? Is it even possible ?“
I close with a quote of a quote in the New York Times “‘We have got to get going,’ Dr. Lanzaro said. ‘We can’t just keep saying 10 more years, 10 more years. Six million people have died while we’ve been fiddling around.’”
Vulnerability to the malaria virus went to fixation in that mosquito species almost certainly because the genes that pluripotently enabled it increased fitness in some way. That means that the less fit altered mosquito will be fertile ground for a new mutation that increases fitness while again enabling malaria. Note also that there are other mosquito species that also transmit malaria.
That fitness might have been “not dying” or otherwise not being harmed by the parasite.
@Rick,
Malaria isn’t caused by a virus, it’s caused by a protozoan.
As for the selective advantage to the mosquito to carry the falciparum protozoan:
“This study revealed that P. falciparium-infected mosquitoes were better at sensing odors than those who weren’t infected. The infected mosquitoes were thus given an enhanced ability to find a blood meal, and so the parasite’s chances of finding a host for the next stage of its life cycle were also improved in a mutually beneficial relationship. The findings have been published in Scientific Reports.
Not only do mosquitoes carrying the parasite get better at smelling stuff, the researchers noted that the mRNA they carry is like what is found in younger insects. If the mRNA molecules in a cell are analyzed, they reveal a snapshot of genes that are active at some point in time. Infected mosquitoes were expressing genes that younger insects would.
“Infected mosquitoes revealed a physiology that had all the hallmarks of younger animals: more focused on reproduction, more robust immunologically and generally fitter than their uninfected middle-aged control siblings,” explained study co-author and Professor of Biological Sciences Laurence J. Zwiebel. “This suggests there is broad generalized adaptive advantage to keeping malaria pathogens in the population. That, in part, explains the global persistence of malaria.”
https://www.labroots.com/trending/microbiology/21757/malaria-parasite-mosquito-host-advantages
I understand why people are nervous. The last thing we want is that gene drive out there letting various malaria friendly mutations spread rapidly. Logic says that the gene drive will be the first thing to mutate into garbage, but Murphy’s Law says that it might be the last thing and wind up being a serious problem helping other mutations spread. This is something new, so there could be all sorts of blowback.
I get the impression that Sao Tome & Principe has all sorts of challenges and limited public health infrastructure. It might be great to be the politician who presided over the end of malaria, but it would be much less great to be the politician who let a bunch of well meaning foreigners generate a new and unanticipated problem. With only 200,000 people and limited resources, it’s no surprise the country doesn’t have a cohort of public health experts and biologists to even evaluate the plan.
I’d say go for it, but biological stuff has all sorts of risks. Is Sao Tome & Principe up for them?
Ethics of gene drives
Several concerns have been raised about the ethics of releasing engineered gene drives in the wild [18]:
1. Is it ethical to deliberately drive a pest species to extinction? In the case of mosquitoes, there are plenty of other mosquitoes that could potentially fill the Anopheles ecological niche but can’t host the falciparum protozoan that causes malaria.
2. Who decides whether someone can release a gene drive that can transgress national borders? How is this different from release of an invasive species? These ethical decisions will have to be adjudicated on a case-by-case basis by panels representing all the potentially affected nations. While there are “kill-switch” CRISPR-Cas9 inhibitors that could be introduced to limit or reverse gene drives [19], release of transgenic pest species capable of driving a CRISPR/Cas9 kill switch to fixation in a population would thwart future attempts at pest control using genome editing.
Counterbalancing these ethical concerns:
1. Is it ethical to decide not to prevent diseases such as malaria and dengue that kill tens of millions of people every year? Where is the ethical boundary between driving a disease vector to extinction and killing off a species, like non-vector mosquitoes or poison ivy, that are a nuisance but not life-threatening?
2. Is it an ethical imperative to replace the need for pesticides that have collateral effects on human health and/or the environment? How are alternative pest control measures, like sterile male release, to be compared to the risk/benefits of gene drives?
The National Academies of Science, Engineering and Medicine published an analysis of gene drives and their impact on human health in 2016 [20]. While it raises many pertinent issues, it offers no concrete ethical landmarks to guide public debate. While the potential benefits are obvious, the risks are speculative since the technology has yet to be applied in the field.
https://www.degruyter.com/document/doi/10.1515/bmc-2021-0001/html
@rick Malaria evolves too — it can have adapted to mosquitoes
Importantly The adaptationist theory which holds that species evolve to increased fitness is known to be incorrect. In particular, it is incorrect if there is genetic drive (which you will notice there is in this case).
@Kaleberg, you argue that Sao Tome & Principe is poorly suited to dealing with the risks of releasing the genetically modified mosquitoes. What risks ? I note that no one has ever told a story for how the release might harm anyone or anythuing (and that is not for the absense of years and years of blocking release as millions have died un-necessarily).
I do not say that certain deaths count for more than purely hypothetical risks, because there are not even any purely hypothetical risks — no one has come up with a hypothesis in which release causes hard. The better releasing those mosquitoes risk hypothesis is like the unified field hypothesis (in that it doesn’t currently exist).