Engineered Mosquitoes Could Wipe Out Dengue Fever

Christina Valencia points us to a Wired story about scientists who plan to use genetically modified mosquitoes to reduce the population of Dengue-carrying insects. The altered genes cause newly born mosquitoes to die before they are able to breed if they are not supplied with a crucial antibiotic. This is a more aggressive approach than the anti-Malaria work we discussed last year. From Wired: "Mosquitoes pass dengue fever to up to 100 million people each year, according to the Centers for Disease Control and Prevention. Up to 5 million die. If the scientists can replicate their results in real field conditions, their technology could kill half of the next generation of dengue mosquitoes, which scientists say would significantly reduce the spread of the disease. If all goes well the company envisions releasing the insects in Malaysia on a large scale in three years."

Comments

Genetically Engineered Mosquitoes

[nitro316]

WTF? I live in Florida. Several, Several years ago a couple of genius scientists at the University of Florida thought it would be a great idea to release Love Bugs into our environment to breed with the mosquitoes and effectively make them sterile. Well, if anyone has ever been to Florida during the summer, then you know that not only are there an ass load of huge fucking mosquitoes but also a shit load of love bugs. Way to go UF~! So now lets releases genetically engineered super mosquitoes into the environment. Things will be much better!

Also all hail our new high powered mosquito overlords!

Are mosquitos important?

[rastoboy29]

I have often wondered (living in the mosquito-ridden South), if mosquitoes have any benefit to the ecosystem at all.  We often hear about how if you remove one creature from the ecosystem, the whole thing changes.  But mosquitoes?  I'm not sure they would be missed by any creature. 

Re:Are mosquitos important?

[MichaelSmith]

Bottom line is that Mosquito larvae are extremely beneficial to ecosystems (as food)

Back when my wife and I had just bought our house I installed two small ponds. Within days we were being bitten alive by mosquitoes. You could see the larvae swimming around in the ponds. We went down to the local creek and returned with a couple of dozen small fish. Within two days we had our result. Hardly any mozzies and fish twice the size.

Won't Work

[theshibboleth]

I don't really understand how the company can expect this approach to work. From the article:

Oxitec's technique is considered less controversial by some scientists because the genetically modified insects are programmed to die, not take over the existing mosquito population.

If the modified mosquitoes are to have any effect they must replace the wild mosquitoes. Otherwise, the wild mosquitoes will still continue to transmit dengue to humans. The article doesn't say whether offspring of wild and modified mosquito live long enough to breed nor what proportion of them still depend on tetracycline, but if you have two populations, one that dies young and another that doesn't and is thus able to breed longer, the longer-lived population will outcompete the short-lived one. Thus if the goal of this is replacement, that too would not work. At best they could hope to kill off maybe half of the mosquito population and thereby reduce dengue fever in the short-term, but doing so could unbalance the ecosystem and potentially have negative effects, including disease, for humans. Maybe a better approach would be to create mosquitoes that only die if they are infected with dengue fever.

Re:Won't Work

[Big Bob the Finder]

Just a stab in the dark, as I don't really have any special insight here. But it would seem likely the concept is to breed large quantities of GMO'd mosquitoes in the lab (providing them with the antibiotic throughout their life cycle), and then release them into the wild. They would then mate with wild-type skeeters, producing offspring with the gene. When those offspring fail to reach maturity because of the absence of tetracycline, it reduces the number of mosquitoes in the wild.

This is not exactly a new concept, although the implementation is quite different. Cattle screw worm (which was a serious economic pest) has been eliminated from North and South America from an aggressive irradiation program in which larvae are reared in large numbers, and then irradiated with cobalt-60. Insert your own "huge, radioactive flies" joke here, but the net upshot is that the irradiated flies mated with irradiated flies and failed to produce fertile offspring for whatever reason. Fewer fertile offspring is a good thing when it comes to population control of undesirable cattle parasites.

Similar programs with Mediterranean fruit flies have been used to control or eradicate populations, but there were some issues a few years back with making sure they really were sterilized by the procedure.

So, it's nothing *that* new, and variations on the technique have proven useful in the past. Now instead of green, glow-in-the-dark flies, we'll just have mutant, GMO'd mosquitoes. Life goes on- hopefully without dengue. Maybe someday without malaria.

flying needles

[tonyahn]

what will they come up with next? Maybe they can genetically alter the mosquitos to carry our flu shots.

The Eco-Nut replies are telling

[ZWithaPGGB]

Lots of people worried about birds or "The Ecosystem". Very few seem to be worried about the millions of PEOPLE who die HORRIBLE DEATHS thanks to Dengue fever.

I guess it's to be expected from the "Silent Spring" crowd, who refuse to acknowledge that the REAL effect of banning DDT has been millions of deaths from malaria, against a hypothetical doomsday scenario. Sound familiar?

Re:The Eco-Nut replies are telling

[raehl]

What is pretty interesting, however, is the mosquitoes don't seem to worry much about the millions of people they're removing from the ecosystem.

Re:The Eco-Nut replies are telling

[Cassius Corodes]

Like you said - DDT loses effectiveness over time. It started out as 95% effective - and ended up being 5% effective in the regions it was most used in. So we couldn't have kept using it forever anyway.

Re:Didn't we learn

[tomhudson]

Until we get anti-anti-biotic-resistant (or whatever you'd call them) skeeters ...

We could also go the other route - reduce the affected population of humans by half ...

Seriously, it won't work unless its done every year - a real cash cow.

Oxitec's technology is a variation of a proven process called "sterile insect technique," which scientists have already used to eliminate the screwworm and the Mediterranean fruit fly from North America. It involves irradiating male insects, causing mutations that make them sterile. When released into the wild, they mate with females who then fail to reproduce.

But the amount of radiation used in that technique kills mosquitoes. So in a twist on the sterile insect technique, Alphey discovered a way to genetically program the bugs to die unless they're fed the common antibiotic tetracycline.

By postponing death with tetracycline, the scientists can keep the altered bugs alive long enough to breed them in large numbers. When released into the wild, they no longer receive tetracycline so the previously silenced gene springs into action. The bugs stay alive long enough to breed with wild females, but their offspring die young.

In other words, the mosquitoes are genetically poisoned, but Alphey's team provides the antidote until they are released in the wild.

"It occurred to me that this could be used to give death, sterility or whatever you want in insects," Alphey said.

Sure, you reduce the next generation of bugs by half ... and then what? Its not like they won't stop breeding, and those that are left will quickly fill the void. Besides, it doesn't take millions of insects to infect you - get bit, get sick. Eliminate half the bites, you'll still get sick.

Re:Whatcouldpossiblygowrong

[Max Littlemore]

Actually it was European humans. From this story, it looks like they're about to strike again.

Re:Ripple Effect

[Dutch Gun]

I'm fairly certain that if someone you cared deeply for was at serious risk of catching Dengue, you really wouldn't give care quite as much how the ecology would fare without those mosquitoes.

Oh, and take a walk out in a tropical region sometime. You'll quickly realize that the notion of the eco-chain being in any significant peril because one species of insect disappears is a bit far-fetched, I think. The number of insects (both in general number as well as the number of species) is pretty staggering. Species have disappeared all throughout history, and nature is fabulous at filling available niches.

I'd have no hesitation in pulling the trigger if it mean eliminating every damn mosquito on earth. Sorry if that sounds unenlightened.

Re:Whatcouldpossiblygowrong

[Kadin2048]

Well, if you consider the megafauna, European humans were probably only the last of a long line of troublemakers on that (as well as other) continents. Driving other species into extinction is something we seem to do fairly well, and have tens of thousands of years of practice at.

Interestingly though, I've read in several places now the theory that human agriculture may have been developed in direct response to our destruction of the animal herds that hunter-gatherer culture depended on. Civilization, such as it is, can be viewed in one light as a coping strategy when our much easier original lifestyle was no longer practicable.

Re:Didn't we learn

[Rei]

Seriously, it won't work unless its done every year

Well, there's an easy solution for that. Genetically engineer them to make them go extinct.

This article on Slashdot is proposing something a *lot* more tame than the specicide proposal. Basically, most genes have a 50% chance of passing on to offspring, but certain "selfish" genes game the system and all but guarantee that they're passed along. So, you make a selfish, lethal, recessive gene -- that is, a mosquito can have one copy and survive just fine. When it mates with a wild mosquito, it'll produce offspring that almost all have the recessive, lethal gene. This will continue until most of the wild population now has the gene -- and then they all start dying off. They can no longer interbreed.

Because it sweeps through so fast, there's no chance to adapt resistance. The only thing that can save the species is isolated pockets that manage not to interbreed with the outside world, then escape after all of the others are dead. Hence, effective, widespread distribution of the engineered individuals is critical for complete specicide. As for side-effects, not only has localized extinction of the Anopheles mosquito not had any adverse impact on the ecosystem (other insects fill in the gap on the food chain), but current control attempts are not mosquito-specific; they kill *many* species in large numbers, and we do it every year.

Re:The environment arguments are one-sided

[khallow]

Take reproduction: in the poorest areas of the world, children are a "positive investment" - they provide free labor and are cheap to raise. This is obviously different in the U.S., where kids cost hundreds of thousands of dollars to raise and parents are lucky if they'll mow the lawn once a week. Plus, for a U.S. woman to have and raise a whole bunch of children incurs a large opportunity cost, because that woman could otherwise have a decently-paying job; in many parts of the world, economic opportunities for women outside of childbearing are very scarce.

Indeed, I think that sums it up nicely.

Now, let's say we wipe out all the mosquitos in sub-Saharan Africa and cure malaria and a whole host of other diseases. This will indeed help the people in those areas short-term and on an individual level. But it's not like as soon as they get off the sickbed they're going to go to work as accountants and tech support workers. They STILL won't have any infrastructure or economic opportunities, especially the women, and therefore they'll continue to chop down forests and have more children than can be supported.

My take is a little different. They will have some infrastructure and some economic opportunity. Not enough to undo a civil war or anarchic kleptocracy (a government barely capable of stealing from you) on its own. But it should be a significant boost even for the worst regions.

Now, I'm not saying you're wrong. Far from it. But I do think it's overstating the situation to say that killing these mosquitos will improve the social and economic situation of the affected people enough to alter their effect on the environment on a large level.

Actually, I disagree somewhat. We look at these regions as screwed up because of how they are organized. That is, bad governance causes disease outbreaks. But it's worth considering that maybe things also go the other way. Namely, that disease breaks society and government as well. For example, the worst HIV infected countries have all gone downhill. I doubt that the US would be running on such an even keel, if a significant fraction of the population were infected with malaria or HIV. One of the large genocides of the 19th century was in the Congo, then known as the Congo Free State. It is thought that most of the deaths from that genocide were due to disease, especially malaria the "sleeping sickness" or African trypanosomiasis spread by the tsetse fly. As I understand it, the typical African village of that region was surrounded by farms. That provided a buffer that the mosquito and tsetse fly couldn't live in. But with the advent of the Belgium-led exploitation of the region, it turned out that for growing rubber vines it was cheaper to kick villagers off and take the already cleared farmland than to clear rainforest (there's a picture of a town leveled for such a rubber plantation). Also, razing was an effective tactic for dealing with rebellious inhabitants as well. Kill those who don't run off, destroy the village, and let the jungle diseases finish the rest.

But I suspect that if disease wasn't so prevalent in the Congo, then the Belgians wouldn't have been as successful and in control. There would have been a lot more live and feisty natives to deal with. I guess my point is that a infamously evil (even by the standards of the 20th century) government was aided tremendously by diseases that preyed effectively on the homeless.

AND 28 Days Later...

[EdIII]

Milla Jovovich is naked on the shower floor........

I'm reminded of both Resident Evil and Aeon Flux, in that our arrogance destroyed the world on one hand and our rush to find a solution made us sterile on the other.

At least this company is doing this to save millions of lives. I can respect that and genuinely admire the scientists that have worked hard to do this. Monsanto programs organisms to die to protect intellectual property profits. I condemn that wholeheartedly.

I DO just LOVE these "mad scientists" though. We have been studying genetics, at the DNA and gene level for what.... a few decades? Now we already have the confidence to introduce organisms into the environment with altered genes which program them to die. I guess I have been in cave and missed all those extensive scientific peer-reviewed studies of the mosquitoes effect on those specific environments. Their specific interactions, their exact place in the food chain, etc. We don't need all that. It would take too long, lets just press the button now and find out what happens. We're so smart and capable and our "hairy reasoners" can come up with a solution if something bad happens. If I really have been in a cave and we have all that groundwork done, peer-reviewed, and verified we STILL don't have the experience of "programmed death" out in the open. I really do think that is shortsighted to believe that the world is so huge that we cannot have any large scale impact on the environment and ecosystems. It is even more shortsighted to believe that we fully understand genetics and these altered genes cannot hop from organism to organism. AFAIK genetic alteration can only occur through a few methods and viruses transmitting new codes into existing organism is one of them. I don't know everything about it, but I know enough to be nervous.

I appreciate the poster who pointed out that there are so many unknowns on either side, the ignorance of the real longterm effects is not a justification for inaction given the consequences of it. However, I would still point out that we are talking about introducing sterility into a population through a brand new science which is still not largely understood. One could argue otherwise, but I think it is overconfident or downright arrogant to think we have come that far that quickly.

I don't live in a tropical locale and I have tremendous empathy for those populations that do live there and have to watch children die due to these diseases. It's very easy for us to judge from a distance and weigh the pros and cons when our lives are not being weighted and measured. I know at some level I am being hypocritical, since my standard of living in the US DOES help destroy the world on a daily basis.

However, I will risk playing the role of the hypocrite, by asking if we really need to provide the solution in this way? We are not attacking Dengue Fever here. We are attacking its distribution mechanism to get at it indirectly with unforeseen consequences to the ecosystems which we are modifying. I instead favor their other method of developing an inoculation for the mosquitoes against the virus in the first place. A much more sensible and less risky proposal.

I also find it interesting that the discussion seems to have split into the "Eco-Nuts" Vs. "Manifest Destiny Assholes". Question the science and its impact on the environment and your an Eco-Nut, favor the human populations and invoke emotions you are shortsighted and arrogant. Perhaps there is a middle ground.

Re:the way this evolution 'thingy' works ..

[redxxx]

I'm pretty sure you are right, as just earlier this year there was an example of the very rapid evolution in an insect population you describe. It was with butterflies and on an island, and the disease in question only affected the male half of the population. The disease in question was very virulent, and this lead to a very strong selection of those with immunity and almost zero competition from those who were not. The immunity spread throughout the population within a few generations.

In this case, there are already many mosquitoes that would not be effected by this. Though in the short term it would likely have some effect, unless it was repeated every single year, pretty much forever, the mosquito population would likely rebound rapidly. It, of course, is not the same exact situation, but it does point to the resilience of insect populations, and the ability of highly beneficial genetic traits to rapidly spread within them.

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