Mutant mosquitoes to wage war on malaria

Genetic engineering has given scientists a frightening new power: to wipe out an entire wild species by altering its DNA. This dramatic ecological meddling could save millions of human lives.

Scientists fighting tropical diseases are pioneering a bold and controversial new strategy: releasing millions of genetically engineered mutants into the wild in an effort to stop deadly illnesses from spreading.

Target number one: malaria, one of the most lethal diseases on earth. In Africa, it kills a child every half hour. Drugs to prevent it are expensive – and there is no real cure – but a new approach offers real hope. Rather than focussing on the disease itself, scientists are now focussing on the creatures which carry and spread it through human populations: mosquitoes, which transfer pathogens from one person to another when they bite.

So what are these 'mutants' and how do they help? The mutants are genetically modified versions of the mosquitoes which spread disease in the wild. When released, they behave just like ordinary mosquitoes, flying, feeding and – crucially – breeding.

But, deeply buried in their DNA, the mutants carry a hidden genetic curse. The offspring they produce when they mate with ordinary wild mosquitoes will survive through the larval adolescent stage but, just before reaching adulthood, they will die, poisoned by a lethal code within their own genes. The scientists hope that entire generations of larvae will perish, with catastrophic effects on the mosquito population.

This year will see the biggest ever release of these 'autocidal' mutant insects, as part of a trial aimed at combatting dengue fever, which is also spread by mosquitoes.

If it works, mutants could soon be seen buzzing all over the world, carrying secret biological weapons to destroy their wild cousins. And these weapons are getting more sophisticated all the time. One new idea is to build a gene that prevents female mosquitoes from flying while leaving male mosquitoes healthy to continue spreading the deadly mutation throughout the population.

Another scheme is to create a child-killing gene that only activates when both parents are carrying it. What makes this last idea particularly frightening is that you could, in theory, wipe out an entire species by introducing only a handful of mutants.

Two-edged sword

This technology gives humanity an enormous and terrifying power over life and death for a whole species. Any kind of creature, not just insects, could be targeted by this sort of genetic warfare – even humans.

Counted against that must be the amazing opportunity to eradicate diseases that kill millions of people each year, mostly in the developing world – diseases about which little can currently be done. Gene warfare is a powerful and perhaps dangerous tool, but it could do an awful lot of good.

You Decide

  1. Is using mutants to cure disease a good idea? Why / why not?
  2. Is technological progress always a good thing? Is science sometimes a force for evil in the world?

Activities

  1. Do some further research into genetic modification of plants and animals. How does it work?
  2. Three kinds of killer mutation are in the pipeline for disease control: one that makes all offspring die; one that makes all females die, and one that makes all offspring die but only when BOTH parents carry the gene. Use charts or graphics to show how these different mutations might spread through a population of mosquitoes. How are they different, and why is the last also potentially the most deadly?

Some People Say...

“This is the thin end of the wedge.”

What do you think?

Q & A

Is this really the only way to control malaria? Aren't there pills for that?
The pills have serious side effects – but, most importantly, they are expensive. Malaria generally affects the poorest parts of the world, which means few people can afford expensive drugs.
And this genetic approach is cheaper?
Hopefully yes. The cost of developing the technology is high, but once the science is done, you only have to introduce mutants into the wild a certain number of times.
How dangerous is it?
Not dangerous if used wisely – but as with all powerful technologies there are risks.
Could this new technology mean the end for mosquitoes?
No. Only for the 'anopheles' species of mosquito which carries malaria.

Word Watch

Genetically modified
Genetically modified organisms, or 'GMOs' for short, are organisms whose DNA has been artificially manipulated by humans. The usual technique is to use a virus to implant an extra strand of DNA into embryonic cells. The organism that grows from that embryo will then have the extra strand incorporated into its DNA.
DNA
Short for 'deoxyribonucleic acid', DNA is a highly complicated chemical compound which contains coded instructions for the growth and reproduction of living tissue. All organisms have their own unique genetic instructions, encoded in their DNA.
Larvae
Many insects have multiple different stages in their life cycle, and can radically change form before reaching adulthood. One famous example is the caterpillar's transformation into a butterfly. Mosquito larvae are adolescent mosquitoes. They live underwater and look somewhat like maggots.
Autocidal
'self-killing'.

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