Effect Measure

This is definitely a good news public health story. So why do I have that nagging feeling that in a year or two or a five we might be reporting it as one with unintended consequences?

I hope not. Here it is:

Mosquitoes genetically engineered to resist infection with a malaria parasite outbreed their normal cousins and might be used to help control malaria, U.S. researchers said on Monday.

They said their study suggests that releasing such genetically altered insects could help battle malaria, which kills up to 3 million people a year around the globe, most of them small children.

Marcelo Jacobs-Lorena and colleagues at Johns Hopkins University in Baltimore studied mosquitoes with an extra gene spliced in that helps stop them from transmitting the Plasmodium berghei parasite.

Previous studies have already shown that these mosquitoes are perfectly healthy.

Jacobs-Lorena and colleagues studied the mosquitoes as they bred in cages. The mosquitoes were allowed to feed on mice that had been infected with P. berghei, one of the parasites that causes malaria.

The transgenic mosquitoes were more fertile and less likely to die than normal, wild mosquitoes, they report in this week’s issue of the Proceedings of the National Academy of Sciences.

They also began to outbreed the normal mosquitoes.

“To our knowledge, no one has previously reported a demonstration that transgenic mosquitoes can exhibit a fitness advantage over nontransgenics,” the researchers wrote. (Reuters)

Good news, really. P. berghei doesn’t cause the worst kind of malaria, but it’s bad enough. This is definitely a promising breakthrough.

Definitely. Definitely. (So why do I keep hearing this little voice saying, “It’s not nice to fool Mother Nature”?)

Comments

#1 qetzal
March 20, 2007

One obvious question is whether the modification alters the mosquitos’ ability to transmit other diseases.

Another scary scenario: we release these mosquitos into the wild. They outbreed the natives and become dominant. Meanwhile, P. berghei (& other Plasmodium spp.?) develop ‘resistance’ to the genetic alteration. Not unlikely, since it’s apparently a single gene modification.

Result: more fertile and more robust mosquitos that transmit the ‘resistant’ parasites, possibly increasing malaria rates in the long run?
#2 Mark
March 20, 2007

It’s fine to fool mother nature. That crazy lady is always trying to kill us with her mosquitoes and plagues and poison monkeys.

I just wish we could kill of mosquitoes entirely, like we did with the screw worm by introducing sterilized males. Now there’s a parasite no one will miss (and no one does since it was a North American parasite and no one remembers it).
#3 G in INdiana
March 20, 2007

Because just about every time we have fooled with Mother Nature, she ends up swatting us in the behind with something even worse than what we supposedly were trying to improve/cure/abolish.
#4 Attack Rate
March 20, 2007

Another voice of concern about other diseases which may be transmitted by bountiful, fertile, long-lived mosquitos.

Also, living with a highly allergic family member, who develops generalised urticaria from a single bite – who wants mosquito bites, even if they can’t give you malaria??
#5 brtkrbzhnv
March 20, 2007

Because just about every time we have fooled with Mother Nature, she ends up swatting us in the behind with something even worse than what we supposedly were trying to improve/cure/abolish.

And that’s why there are a million times more of us now than before all the chicanery.
#6 caia
March 20, 2007

Transgenic mosquitoes even better at reproducing than the regular kind? What could possibly go wrong?

And when they get out of control, I’m sure we can reduce their numbers by bringing in cane toads.
#7 rehana
March 20, 2007

I’d say the parasite is most likely to evolve the ability to infect them anyway.
#8 Melanie
March 20, 2007

Add my voice of concern, over the “Law of Unintended Consequences.”
#9 Nancy
March 21, 2007

Hmmmm…do you think that nagging voice has anything to do with the balance of nature, population control, or overburdened resources?

I don’t know how or why humans came to the belief that it is OK to breed like rabbits to the point of gross overpopulation and natural resource depletion. Disease serves a function. Curing disease by tinkering with nature is a very slippery slope.
#10 SoCal
March 21, 2007

My nagging voice is saying that if they didn’t predict that their manipulation would produce super-breeders, they they probably don’t understand enough to foresee what unintended consequence the super-breeding will produce.

Define “perfectly healthy” mosquito, please. I don’t think scientists know enough about the mosquito genome to do that. I’d love to be wrong.

And will the public, who will have to live with the unintended consequences, be able to vote on whether the genetically-modified mosquitoes will be unleashed upon us? Not a chance. For the human race, I mean… we have not a chance.
#11 Jo�o Carlos
March 21, 2007

People, read the original work. The trangenic mosquitoes are more fertile and less likely to die than normal, wild mosquitoes WHEN FEED WITH INFECTED MICE. WHEN FEED WITH NORMAL MICE, both strains of mosquitoes have the SAME FITNESS.

The trangenic mosquitoes aren’t super-breeders. They have superior fitness only at environments with P. berghei. Feeding at populations that don’t have P. berghei THEY HAVE NO FITNESS ADVANTAGE. So, I guess they will not eliminate completelly the wild mosquito. Higher the trangenic gene at the mosquito population, lower the number of people and animals infected with P. berghei, lower the selection against teh wild breed. That is Frequency-dependent selection! Balancing selection! Go read a book about population genetics, fast! Learn something about natural selection!

I think that big problem is that there are a lot of people that don’t understand evolution and NATURAL SELECTION. Shame you all!

Overall, the trangenic mosquito can lower the number of cases of malaria, maybe enough for the health system at third world poor countries have a chance to eliminate the disease. But if they work fast before P. berghei evolve to infect the trangenic mosquito.
#12 quitter
March 21, 2007

Nancy, you’re one sick individual. Seriously, go live under a rock with all the other anti-medicine creeps.
#13 anon
March 21, 2007

Not that it necessarily pertains to the discussion but the story reminded me of an old nursey rhyme.

There once was a lady who swallowed a fly. I don’t know why she swallowed the fly, I guess she will die. There once was a lady who swallowed a frog, she swallowed the frog to swallow the fly. I don’t know why she swallowed the fly, I guess she will die. There once was a lady who swallowed a snake, she swallowed the snake to swallow the frog, she swallowed the frog to swallow the fly. I don’t know why she swallowed the fly, I guess she will die.
#14 Lea
March 21, 2007

anon: The song Leave Well Enough Alone comes to my mind. Can’t recall all the lyrics or even who sang it. Might even be from a childhood cartoon character.

quitter: your comment to Nancy is ridiculous in my eyes and your response childish.

Nancy: Liked what you said, ignore the heckler.

~~~~~~~~~~~~~~~
#15 M. Randolph Kruger
March 21, 2007

Quitter-Uh Nancy is only posturing something that is taught in the war colleges of the United States of America. I have visited your site and it doesnt seem to be too far off the beaten path. Most people here try to keep it a little more intellectual than trying to stomp down any ideas. I have my ideas of how most things should be in the world, Revere is pretty much diametrically opposed to MUCH but not all of what I say. We all agree that there are probelms in the world and the suggestion that Nancy was some sort of crazy is not founded in anything other than a thought that she MIGHT be anti-medicine.

Revere comments on this kind of stuff all the time. I dont try to quash it unless there is something really valid out there to do it with, namely science. Al Gore is a good example. One of the Reveres teaches some sort of environmental course at the university in which they are resident. I find that the science that Gore uses is bent to the agenda and while my side of the fence agrees that some global warming is occuring and it could be man induced, it might also be induced more by other things. RF oscillation of the core of the earth producing heat (eg. microwaves from the electric fields we are generating) to Milankovitch cycles. He has his ideas, my side has ours. Problem is no one can PROVE it. So lets not smack down Nancy as some wild eyed tree hugging crazy. Why? I believe that part of the course work to become a doctor denotes the direct relationship between food supply, medicines to combat diseases that are common such as the clap (gonnorhea), polio, typhoid, tetanus etc. Tinkering with mother nature has been going on since someone grabbed a leaf to cover a wound and found that it had a narcotic effect on it. Thats tinkering if you want to call it that. I’ll bet that Nancy like her dog if she has one, has all of her shots.
#16 crfullmoon
March 22, 2007

(I bet Nancy and MRK could have a civil,
interesting, chat at a tea party, too. Scones and Scotch?)

qetzal and Attack Rate said it already;
we have no idea what these mosquitos will do in terms of
all the other mosquitor-vectored diseases!
I really hope they will try a more natural mix of diseases predators and prey in the lab first, before they dump then in Africa or wherever. What happens if they are exposed to pesticides that may or may not be being used correctly?
Too many “unknown unknowns”.
(Uh, and what if those mosquitos are in a rice-with-human-genes paddy ? Genes may jump when and where they aren’t supposed to- can’t “spliced” things come “unspliced”?)
#17 Susan Och
March 22, 2007

I kept looking for the line in the story that said that they let the mosquitoes bite uninfected mice (after infected mice) and the uninfected mice didn’t get sick.

Maybe I’m unsophisticated, but until I read that line, what’s the big deal?

Meanwhile, what about the possibilty of hybridizing with some other strain of mosquito? What exactly is the mechanism by which the new mosquitoes are prevented from carrying the parasite?

Birds eat mosquitoes. Over a few genrations, birds can alter the routes and timing of migrations to take advantage of better (or worse) food sources. Given the current paranoia about migrating birds, do we really want to start fiddling with the mosquito population?
#18 revere
March 22, 2007

Susan: The main point is that mosquitoes are intermediate hosts. The malaria parasite has to undergo some of its life cycle in the mosquito, which is thus more than a flying needle. So if the mosquito is no longer a competent host it is also not a competent vector.
#19 M. Randolph Kruger
March 22, 2007

Revere, I want to pose a question to you and give me your FWIW thoughts. I agree with the bunch above and you that screwing with Mother Nature aint the brightest thing we have ever done. Growth hormone in cow feed, aeromycin in bag loads into pig food. You know the drill.

So far like G in Indiana says we get smacked every time we fool with it. But thats our yardstick. We do something and it produces an effect. That effect is either good by our yardstick or not. We all remember adaptation from HS. Science. The effect of releasing neutered mosquitos would cause irreparable harm to bats and other species that feed on them such as frogs. Cant breed if you arent there. Cant move malaria around if they are dead or never born.

On the other hand if we do that might not some other disease rear its head up and take over where we forced it to leave off? In history and thats the big question really because you guys have studied this overall, does what we do have anything more than a temporary effect? In history did and does what we do have a measureable effect and then somethng rolls in and takes its place?
#20 revere
March 22, 2007

Randy: Well, I’m of two minds, which I tried to express in the post. As you pointed out, we fool with Nature all the time. That’s our nature. There are just somethings when I read them that a little voice says “oh, oh” and this was one of those times. I was thinking out loud. Mainly I think it’s good they have a way to attack a disease that is really, really bad. I just worry that releasing free living genetically modified species that are disease vectors into the environment as danger signs all over it.

So I’m not automatically against it (as I say, we are doing it constantly) and even in this case I have an open mind. But part of that open mind has some uncomfortable doubts. I’d tread pretty carefully.