End of DEET?

Sept. 30, 2013, 5:51 p.m.

U.S. scientists are working on an 'invisibility cloak' for mosquito-plagued people, pets and livestock.

The researchers have discovered substances that occur naturally on human skin and block mosquitoes' ability to smell and target their victims.

Scientists believe the research could be another step in the fight to stamp out deadly diseases such as malaria, which kills approximately one million people around the world every year.

Speaking at the National Meeting & Exposition of the American Chemical Society, research chemist Ulrich Bernier said that far from being a nuisance, mosquitoes are more deadly to humans than any other animal.

In the U.S. alone, mosquitoes spread rare types of encephalitis, an inflammation of the brain as well as transmitting heart worms to pet dogs and cats.

Dr Bernier said: 'Repellents have been the mainstay for preventing mosquito bites.'

The most widely used repellant, DEET, is quite effective and has been in use for a long time but some people don't like the feel or the smell of the repellant, he said.

'We are exploring a different approach, with substances that impair the mosquito's sense of smell. If a mosquito can't sense that dinner is ready, there will be no buzzing, no landing and no bite,' he explained.

Female mosquitoes, which suck blood to obtain a protein needed to produce fertile eggs, can smell people from over 100 feet away.

A person's scent, Dr Bernier explained, comes from hundreds of compounds on the skin, many emitted through sweat and others produced by bacteria.

To identify which of these attract mosquitoes, Bernier and colleagues at the Mosquito and Fly Unit at the U.S. Department of Agriculture's Agricultural Research Service Centre for Medical, Agricultural, and Veterinary Entomology in Florida, used a special mosquito cage divided by a screen.

They sprayed various substances into one side of the cage and documented the effects in attracting mosquitoes.

Some compounds, like lactic acid - a common component of human sweat - were definite mosquito lures, drawing 90 per cent of the mosquitoes to the screen.

With other compounds, however, many of the mosquitoes didn't even take flight or seemed confused.

Dr Bernier said: 'If you put your hand in a cage of mosquitoes where we have released some of these inhibitors, almost all just sit on the back wall and don't even recognise that the hand is in there.

We call that anosmia or hyposmia; the inability to sense smells or a reduced ability to sense smells.'

He said that a group of chemical compounds, including 1-methylpiperzine, block mosquitoes' sense of smell.

This may help explain why mosquitoes fly toward some people but not others.

The substances have a molecular architecture found in ingredients in dozens of medicines and other products and they appear suitable for use in cosmetics, lotions, clothing and other products that currently incorporate mosquito repellants, he said.

The Mosquito and Fly Unit has been doing research on mosquito repellents since the 1940s.

In the 1990s, it accumulated information on substances secreted through the human skin or formed by bacteria on the skin that make some people more attractive to mosquitoes than others.

 

Read more: http://www.dailymail.co.uk/sciencetech/article-2416663/The-end-DEET-Scientists-developing-mosquito-invisibility-cloak-replace-repellents.html#ixzz2gOponY7B

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