Each year hundreds of millions of people are stricken by dengue. Though there are thousands of species of mosquito, just one is to blame for major outbreaks of dengue – the Aedes aegypti mosquito. This highly invasive mosquito is in more than 100 countries and is still spreading.
There are no licensed vaccines or specific drugs for dengue, so the only way to control the disease is to control the mosquito that spreads it. Unfortunately the available tools just aren’t working adequately, and the mosquitoes are becoming resistant to the pesticides we use. Those chemicals can also harm helpful insects like bees and butterflies. So there’s an urgent need for better methods.
The invention nominated for this award is very simple – harnessing the mosquito’s reproductive instincts as a way to reduce their numbers. Genetically engineered male mosquitoes (male mosquitoes don’t bite) are released to mate with females. Their offspring die before they can reproduce or become transmitters of disease. The engineered males are in effect sterile, so if enough female mosquitoes mate them the target population will decline and collapse1.
Originally developed at the University of Oxford, this technology is being taken forward by Oxitec Ltd, a biotech company that I helped set up for this purpose. More than 90 million Oxitec mosquitoes have been released in approved trials worldwide, with unprecedented success in controlling the dengue mosquito: in every trial the target mosquito population has been reduced by more than 90%.
In Brazil right now, the dengue burden is so great they’ve called in the army to help educate people on how to fight the dengue mosquito. Brazil has a lot of experience and expertise in tackling dengue and recognises the need for new approaches to complement and improve on current methods. The national biosafety group (CTNBio) has approved Oxitec’s engineered mosquitoes for release throughout Brazil. Piracicaba, a city in Sao Paulo state, will start releases of Oxitec’s mosquitoes at the end of this month, following previous successful trials in Bahia state.
I was recently reading a piece in The Biologist about Rachel Carson. Though she was writing before modern genetic methods were available, she commented favourably on an earlier sterile-male method that used radiation to sterilise the males. In Silent Spring she wrote:
“Now at least, as it has become apparent that the heedless and unrestrained use of chemicals is a greater menace to ourselves than to our targets, the river which is the science of biotic control flows again, fed by new streams of thought.
“Some of the most fascinating of these new methods are those that seek to turn the strength of a species against itself – to use the drive of an insect’s life forces to destroy it. The most spectacular of these approaches is the ‘male sterilization technique’”…(which she goes on to describe in some detail).
My dream is to take this method to a scale where very large areas are saved from epidemic dengue – we’re not there yet but all the data so far indicate this is achievable.
It is an honour to represent the UK as our only nominee for the EPO European Inventor of the Year Award. I’m very grateful to the European Patent Office for their recognition of this biotechnology breakthrough because I believe it will help people around the world to become aware that there are new effective, safe and environmentally friendly ways to control disease-carrying mosquitoes.
One part of the award is by popular vote – if you’d like to vote for this invention you can do so every day until Thursday 4th June.