Nearly a billion people are affected by mosquito-borne diseases all over the world, with a major share in India. More than 40 million people suffer from mosquito diseases like malaria, filarial, dengue, chickungunya, brain fever, Japanese Encephalitis. Come monsoon, there is a spurt in these diseases across the country. India spends over 100 million dollars on malaria alone, which affects an estimated over two million people.
The extent of mosquito-borne disease can be gauged by the fact that sale of mosquito repellents has reached a whopping over 680 million US dollars (Rs. 4400 crores) a year in India.
Over a period of time, mosquitoes have developed resistance to medicines and chemicals. An Indian-born scientist at the US University of California has developed a safer, better-smelling and effective insect repellent.
"The mosquito has an incredibly sensitive nose," said Anandasankar Ray, professor in the Entomology Department at the University of California and director of the Center for Disease Vector Research. Ray has spent much of the past decade learning how mosquitoes detect scents.
When we exhale, we emit carbon dioxide. Mosquitoes have super-sensitive CO2 sniffers, and follow plumes of gas knowing that a tasty source of blood is waiting at the other end. The simplest way to keep mosquitoes from finding you is to confuse them by jamming their scent radar.
Most mosquito repellent on the market today contains a compound called DEET, the go-to since the 1950s. It works well, but why it works has long been a mystery. DEET can also melt your swim trunks, cause a variety of negative reactions and is too expensive to be of true value in parts of the world where malaria and other mosquito-borne illnesses are a serious problem.
Ray started wondering why there had been so little innovation around DEET. A cheaper, effective mosquito repellent without the problems associated with DEET could save lives on a massive scale — surely there was something better out there.
"It turns out that DEET is incredibly complex, or rather, understanding how mosquitoes detect DEET has been a big challenge," said Ray.
Ray's lab at University of California Riverside started trying to understand exactly how mosquitoes detect DEET. First, they found a receptor in the antennae shared widely among insects that can detect DEET. Once they had located the receptor, they were able to rapidly screen chemical databases for safer and better-smelling alternatives that would work in the same way.
"We were able to very rapidly screen nearly half a million chemicals in one afternoon and identify 1,000 new substitutes for DEET," said Ray.
Many of these chemicals come from fruits and plants and are already known to be safe for human use — and, as a side benefit, many of them naturally smell fantastic. Instead of a harsh medicinal aroma, imagine having an effective mosquito repellent that smelled like sandalwood or sweet orange blossom.
"Nearly a billion people worldwide are affected by mosquito-borne diseases," said Ray. "I am hopeful that this approach will lead to interventions that could be useful in the field and perhaps not only help protect us in our backyard barbeques, but also help have an impact on malaria."
Source: University of California
Image courtesy: University of California