Don't let the bugs make you 'whine' - insect repellents - Statistical Data Included

In California, it always seems that when tending to vines and harvesting grapes are at their best, biting insects are at their worst. And when the ubiquitous mosquito attacks, sucking your life's blood away, swiping in the air is futile. Just when you think you've outsmarted these dive-bombing bugs and you find a cool grassy knoll to sit down on for a well-deserved lunch break, you become a lunch break for ticks. When you compound these problems with the rising rates of mosquito and tick-borne diseases, the need for insect repellents becomes an integral part of vine-related activities.

Of the 38% of Americans who use insect repellents, 22% use products containing the neurotoxin DEET (N,N-diethyl-m-toluamide), the active ingredient of OFF!, Deep Woods OFF!, Skintastic, Cutter Pleasant Protection, Backwood and Backyard Cutter and Muskol repellents.

Synthesized in 1954 and marketed as a repellent in 1957, it's considered one of the safest and most effective insect repellents available, and it comes in varying forms, from towelettes and pump sprays to liquids and creams, with concentrations ranging from 5% to 100%. However, DEET products with lower concentrations must be applied more often to ward off insects, so to avoid frequent applications, manufacturers have made products that contain higher DEET concentrations. Furthermore, activities such as sweating and wiping can remove the repellent, consequently increasing the need for frequent reapplication. This, in turn, can cause allergic and toxic reactions.

The most common symptoms include burning sensations on the area of application, drowsiness, dizziness, disorientation, restlessness and headaches. Slurred speech, irritability, explosive diarrhea, confusion, twitching toes and fingers, nausea and vomiting indicate more advanced symptoms. Death has been reported.

Although DEET is effective against chiggers, blackflies, biting midges (punkies or no-see-ums), stable flies, sand flies, bed bugs, head lice, fleas and leeches, most of DEET's research has centered on its repellent properties against mosquitoes and ticks.

Ticks that transmit Lyme disease, a bacterial infection, can be found anywhere in the woods, at the shore or in backyards and can be found all year long, although peak season is April to September in the Northeast and November to April on the West Coast. They hang out on the ends of grass waiting to be picked up by a passing person or animal, which could be you or your pet dog or cat. Antibiotics are effective during early stages of the disease, and last year the FDA licensed LYMErix, the first vaccine against Lyme disease. Given as three doses over a one-year period, the vaccine-induced antibodies enter the tick and kill the bacteria there. Another noteworthy tick disease that can be caught in California is relapsing fever (cabin fever). Although a 20% to 30% DEET concentration is 90% effective in preventing tick attachment, DEET plus a permethrin-containing clothing repellent offers the best overall protection.

Mosquitoes thrive anywhere there is water. Whether a lake, river or swamp, the nook of a tree or the cranny of an old tire, the more than 150 species of mosquitoes in the United States--59 species in California--only need from two to 14 days to develop from a harmless egg to the most pestilent pest known to man. We're talking billions of deaths throughout history. However, there is a simple solution--no bite, no problem.

San Diego County had outbreaks of locally acquired malaria in 1986, 1988, 1989 and 1990. Since California has the mosquito vectors--migrants from malarial areas and large international airports--endemic outbreaks in California are a constant threat.

The most common mosquito-borne disease found in the U.S. is St. Louis encephalitis, which is found everywhere except the Great Lakes.

Another disease of note for California is California encephalitis, and Western equine encephalitis was first discovered in the West affecting horses. Birds carry the encephalitides viruses, so if a mosquito bites an infected bird then bites us, we get the disease.

DEET doesn't actually repel female mosquitoes so much as fool them. The shape of DEET molecules fits into the microscopic openings at the ends of the individual antennal hairs of the female mosquito leaving the mosquitoes with the equivalent of a blocked nose. Without being able to sense the proper odor, the female mosquitoes won't feed, even if they land on you.

Depending on the concentration, DEET can provide protection from mosquito bites for two to 12 hours, though sweating and wiping, which remove the repellent, can reduce effectiveness. For kids, use 5% concentrations; if you're near thick-wooded areas, higher concentrations up to 25% ire usually safe; and for regular vineyard use, recommendations range from 5% to 15%.

DEET alternatives? The EPA registered, natural repellent Buzz Away is rated as the most effective DEET-free insect repellent. Tests show it can give up to 5% protection for up to an hour. What that means is that during the time of exposure to mosquitoes, a person wearing the product might get five or fewer bites. Buzz Away is formulated with citronella, cedarwood, eucalyptus, lemongrass and peppermint. Other natural repellents can contain ingredients like neem and citrus oil, and mosquito candles and coils containing oil of citronella do exhibit repellent properties. A new product on the market called Blocker, which contains 2% soybean oil, is just as effective as a repellent with 7% DEET. Although mineral oil in Avon's Skin-So-Soft can prevent mosquito landings for 30 minutes, subsequent applications have been shown to attract mosquitoes. Furthermore, acoustic devices and oral doses of vitamin B1 are ineffective repellents.

To avoid adverse effects from DEET repellents, avoid applying them around your eyes, lips, wounds or irritated skin, and take care not to inhale sprays. Remember, drenching your body or soaking your clothes in repellent won't make the repellent work any better. Avoid long term use or frequent total body applications, and wash off residual repellent when insect exposure has passed.

Special care needs to be taken when applying repellent to kids. Keep repellent off of children's hands, since they tend to put fingers in their mouths, and out from under occlusive clothing such as diapers. Kids under 6 months old shouldn't be treated with repellents. Repellents should also be stored out of reach of children, since accidental ingestion can be fatal.

And finally, always check the repellent's label for the active ingredients and for directions on safe use.

(Dr. Craig Reed is a freelance writer for Reuters and a former pre-med biology and microbiology professor at the universities of Illinois and Missouri at St. Louis. He has a background in medical entomology, toxicology and Lyme disease research and can be contacted at edit@winesandvines.com.)

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