I hope trying to link this article I just read, works, never tried to do this before. But this article completely blew my mind.Scientists target blood-sucking pests
By Dennis O'Brien
BALTIMORE SUN
You don't have to read the headlines to know that they're nasty creatures. And the news is still bad for people who venture outdoors this summer: We're a long way from wiping out the 60 species of mosquito that spread West Nile virus and the deer tick that carries Lyme disease.
And despite research involving garlic, catnip, eucalyptus and volunteers willing to stand in tubs full of ticks, there is no infallible system for keeping the bugs out of your back yard -- and your bloodstream.
"There's a tremendous push being made to see if we can find something. But there's not many chemicals out there as candidates," said Jerome Klun, an entomologist with the U.S. Department of Agriculture's research lab in Beltsville, Md.
Beltsville researchers have been awarded $4 million in U.S. Defense Department grants to come up with repellents to protect troops from ticks and mosquitoes that transmit malaria, dengue and yellow fever overseas.
To that end, Klun and colleague John Carroll will create their own version of "Fear Factor" this fall when they and other volunteers douse their ankles in three kinds of repellent and step into plastic tubs filled with 100 lab-raised ticks each.
They want to know how many ticks ignore the repellent and crawl up their legs.
The experiment will run for six days as the researchers compare SS-220, an experimental repellent developed by Klun and other Beltsville researchers, with Picaridin, a commercially available repellent, and a solution containing the insect repellent chemical known as DEET.
Carroll, 59, said there's no danger that the ticks are carrying lyme disease. Not only are they lab-raised, they're also lone star ticks, a different variety from the deer ticks that transmit the disease.
Nor does the tub of ticks give him the creeps.
"When I'm out in the field, it's more risky than if I'm standing in a tub and I can see what's going on," he said.
The challenge is the complexity of the bugs.
The pests have 30 million years of evolution on their side, and they've developed unique sensors that zero in on the carbon dioxide and other chemicals we emit. Once they sense us, they use different approaches to get into our bloodstreams.
The female mosquito -- the one that bites -- approaches like a stealth fighter, and once she lands, a probelike cutting apparatus in her head finds our blood, which provides protein to nourish her eggs.
The wingless tick waits in the brush -- sometimes for days -- to snag a ride on a leg, arm, head or neck.
Males and females dig their mouths into our skin, and they can stay attached for days, sometimes leaving poison picked up from other animals as they siphon our blood.
Despite years of effort, scientists still aren't sure what constituent of our sweat and breath attracts the insects, and what best repels them.
Preliminary evidence confirms what many researchers suspect -- that some people are attractive to mosquitoes while others nearby remain un-nibbled.
Ethane, ethanol, acetone and isoprene -- chemicals found in varying amounts in sweat and exhaled breath -- might attract mosquitoes, studies show.
Some researchers are convinced that chemical changes in our sweat, often caused by our diets, play a key role.
Dr. Thiruchandurai Rajan, chief of pathology at the University of Connecticut Health Center, was inspired to check out the effects of garlic on repelling mosquitoes because a colleague's wife was feeding garlic to her horse.
In his experiment, dozens of human test subjects took garlic capsules or placebos and then inserted their arms into a mosquito cage to see whether it had any effect on the number of bites they received.
It didn't. Rajan still suspects that a longer experiment in which subjects eat more garlic for longer periods might show some improvement.
The question is whether eating so much garlic would be more effective at driving away insects or friends.
A big concern among health officials remains the tick's ability to spread Lyme disease and the mosquito's to spread West Nile virus.
West Nile virus, discovered in Uganda in 1937, infected 2,535 people in the United States last year and killed 98, according to the Centers for Disease Control and Prevention.
The virus has caused 260 U.S. deaths and infected 10,000 people since its arrival was documented in 1999.
Lyme disease, named in 1975 after it was first reported in Lyme, Conn., can cause heart trouble, fainting spells, vision problems and arthritis if left untreated.
There were 17,000 U.S. cases last year, according to Kim Mitchell, an epidemiologist with the Maryland state health department's Center for Veterinary Public Health, and CDC reports. Officials say those numbers could increase in the coming years.
Concern about pest-borne disease has spawned an explosion in the market for mosquito traps, zappers, foggers, UV lights, repellents and sprays.
Repellents alone generate about $100 million a year in sales, according to the market research company ACNielsen.
"We've seen tremendous growth," said Gordon Jones, a vice president of Biophysics Corp., a Rhode Island company that sells mosquito traps for $295 to $1,195.
The traps get rid of mosquitoes by converting propane to carbon dioxide, enticing them into a trap, where they are killed.
Running 24 hours a day, a trap will rid as much as 11/4 acres of mosquitoes in 30 days, Jones said.
In 2003, Consumer Reports found that the traps were effective, but its researchers recommended less expensive approaches first, such as repellents and protective clothing.
Only 30 percent of people who venture outdoors ever wear the stuff, surveys show.
"They don't like the way it smells, or they don't like the way it feels on their skin," said Brian Weekley, president of Minnesota-based Bugg Products.
Weekley, a chemical engineer, left the cosmetics industry 11 years ago to create an insect repellent with what he says is exactly the right blend of vanilla fragrance and the proven bug repellent known as DEET. Still, it's a hard sell.
"People are very skeptical about the repellent industry because there's so much folklore and junk out there," Weekley said.
Joel Coats, an Iowa State University entomologist, said it was folklore that attracted him to an oil extracted from catnip, an herb from the mint family named for its intoxicating effect on felines.
Coats is convinced that the oil is one of several botanical products that can repel mosquitoes and could one day be a replacement for DEET.
In 2001, Coats inserted groups of 20 mosquitoes into a glass tube and found that they consistently avoided portions of the surface treated with the oil. The university has patented a synthetic compound made from the catnip oil.
Although most studies indicate DEET is safe, some experts recommend it only in low doses because high doses might cause health problems, particularly when it's combined with other medications or insecticides.
In high concentrations, DEET is also a plasticizer -- if applied to the skin, it will soften plastic surfaces touched by those wearing it.
"If you use DEET in low concentrations, it's not so bad. But we think there's just as good, if not better, repellents out there," he said.
At Beltsville, much of the research is aimed at coming up with a replacement for DEET, the common name for N,N-diethyl-meta-toluamide. It was developed in the 1950s and is a key ingredient in repellents and insecticide sprays worldwide.
Still, DEET remains the gold standard for keeping away mosquitoes and ticks, and most experts say repellents laced with 20 percent to 30 percent DEET are safe.
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