Genetic modification, the antidote?



This weeks post is set around an article from the Guardian on the 12th of November. It was written about the possibility of ridding the world of dengue fever. Interestingly, the same approach could also successfully combat malaria.

If you did not read the article, a group of scientists mean to genetically modify the male mosquito to be entirely dependent on an antibiotic tetracycline – a drug administered to the mosquitoes in the lab. The male mosquitoes die within a few days if they do not receive this drug and so, wouldn’t survive out in the wild as long as they normally would. They would however survive long enough to mate and pass on this modification.

The genetic alteration is geared to be a dominant gene. This would lead to a widespread proliferation of this dependence leading to mosquitoes slowly but surely being killed off, almost like a genetic infection.

The Oxford-based firm, Oxitec, recently trialled this in the Cayman islands and recorded an 80% reduction in the number of mosquitoes over 6 months. That is a huge portion of a species’ population; all to the benefit of the human inhabitants I’m sure! By simply reducing the number of mosquitoes, the number of possible dengue fever infections will decrease too.

There is no doubt that Dengue poses a large threat to people all over the world. There are an estimated 50 million cases of dengue fever a year, of which 25,000 are thought to be fatal. Fortunately I cannot attest to the severity of the flu-like symptoms, which are undoubtedly horrible to endure but at a fatality rate of 0.05%, wiping out an entire species (and probably more than just one,) seems like a drastic touch. Malaria could also be combated in a similar way, reducing the number of vectors and therefore infections.

There is I believe a huge ethical question mark over practices such as this. There are cases where we can use our scientific knowledge to benefit both the planet and us, but then there are also cases where we use it to bully and mould the environment and its gifts to our overly selfish needs (see Global Warming). I believe this case falls alongside the latter.

Mosquitoes aren’t just blood sucking mini-vampires as I’m sure you are aware. It is of course only the female mosquito that drinks blood. The rest of their lifespan is spent feeding off nectar and similar herbivorous resources to the benefit of those plants through pollination in a mutually beneficial way. These highly effective arthropods have changed little from the Jurassic Park specimens from millions of years ago. They aren’t intentionally infecting us with a parasite or virus, it just so happens they are the highly effective tools used to do so.

Albert Einstein once mentioned that if the bees of the world died out, mankind would soon follow. Arguably the repercussions of eliminating entire species of mosquito could be substantial (although in all likelihood not – an environmental hiccough before carrying on as normal with other organisms filling the vacant niche according to Nature magazine.) Do the millions of individual mosquitoes of the 3,500 species have less of a right to live than the thousands of people they infect with deadly diseases? If they have little to contribute to our well-being and apparently no beneficial contribution to the world, why should they carry on living?

Ideally, if we could target the virus or the parasite in dengue and malaria respectively this would remove the need to kill mosquitoes off entirely but it poses a much tougher task given the lack of exposure or opportunity the parasites give us, and the rapidly evolving strains in both cases. There are various developments in this methodology and I’m sure that over the next decade or two either a method of combating the viruses and parasites directly or one that kills off all the mosquitoes will win the race and be accepted by the general public as a means to an end.

What I really ask is, at what price would you put the possible eradication of malaria and dengue fever? How many mosquitoes would you get rid of for the sake of a possible relief from the worry of infections like malaria and dengue.

My own personal opinion, is that prevention of the spread of disease by the use of effective insect repellent negates the need to kill off entire species of mosquito and that all resources should be concentrated on combating the infection directly, not by eradicating the vectors. I would be interested to hear any thoughts on this.

Luke Hampton – Guest contributor

On a lighter note, check out this video!

The mosquito song


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