Do you feel like bug bait?

It's West Nile virus time. And mosquitoes do like some folks more than others

By Katherine Hobson

Posted 7/6/03

Mosquitoes just love Terez Rubenstein. On a recent trip to the Caribbean, so many of them divebombed her head at night that her husband wrapped her up in sheets like a mummy, leaving just one eye exposed and covering her ear with his hand. "I woke up with five bites around my eye," says the 25-year-old from Brooklyn, N.Y. "And my husband only got bitten on the hand that was covering my ear."

Experiments show that, like Rubenstein, some people are just irresistible to mosquitoes, and others, like her husband, don't have the same allure. It's not just a myth. With experts predicting a bumper crop of the mosquitoes that carry West Nile virus this season, the special magnetism is a bit worrisome. West Nile, found in 28 states so far this year--and expected to appear in all 50--causes high fevers in some people, neurological problems in others, and can be fatal. Though the species that carries the virus, Culex pipiens, prefers birds, some people are bitten by accident--or because of how they smell. And even mosquitoes that are virus-free can bring itchy misery.

The good news is that insect repellent does work; people most prone to bug bites simply need more of it. Further, researchers have been teasing out the factors that draw mosquitoes to one person and not to another, and therein lie some clues to reducing your desirability.

Mosquitoes use many cues, including heat and moisture, to home in on their targets. Chemicals are also highly influential. Most species that feed on mammals find them by following the trail of exhaled carbon dioxide. "CO2 is the common denominator," says Willem Takken, an entomologist at Wageningen University in the Netherlands.

Then there's your skin: Scientists have found isolated compounds on the body's largest organ that may attract different types of mosquitoes, depending on how the chemicals are combined. A blend of three--lactic acid, acetone, and dimethyl disulfide--is particularly appealing to the mosquito that carries yellow fever, says Dan Kline, a research entomologist at the U.S. Department of Agriculture's Agricultural Research Service in Gainesville, Fla. Mosquitoes from Brazil and the United States were attracted to slightly different combinations of these chemicals, he says, suggesting attractants also vary by geography.

They also vary by person. Takken's group just completed a study of mosquito appeal among 28 human volunteers. (They used a special chamber that funnels human scents to the mosquitoes but protects volunteers from actually getting bitten.) "There was a consistent difference in who was least attractive and who was most attractive," says Takken. "Some people simply produce more of compound X than compound Z." One study from Australia even suggests your genes may hold the keys to what makes a mosquito decide that you make a good meal.

What can you do? Some things about our bodies and skeeter allure are under our control. Chemicals activated by sweat that sits on the skin seem to attract mosquitoes, says Kline, so staying clean and dry should help. He also suspects medication and diet may play a role--his own experience is that eating lasagna (and the cheese it contains) attracts certain species.

Ideally, all this research would allow scientists to synthesize the attracters for use in traps. One trap, the Mosquito Magnet, uses a mix of CO2 and octenol, a chemical secreted by livestock, to attract biting insects. But variation of feeding habits among mosquito species makes it difficult to attract them all with one chemical cocktail. For example, scientists will need to study avian attractants to figure out what draws the West Nile virus carriers.

For now, the best solution is to cover up and use a repellent containing DEET, especially between dusk and dawn when mosquitoes feed. And if you're an attracter, there's no harm in trying to see if there's a pattern to the biting. On her next vacation, Terez Rubenstein may want to lay off the lasagna.

West Nile on the move

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The virus has already appeared in 26 states this year, and it's only July. By the end of last year (right) it was found in 44.

Bird, animal, or mosquito cases in 2002

Idaho

Maine

N.H.

N.M.

Wash.

Human cases in 2002

Calif.

Colo.

Conn.

Del.

Kan.

Minn.

Mont.

N.J.

N.C.

R.I.

S.C.

S.D.

Vt.

Wyo.

Human cases and deaths in 2002

Ala.

Ark.

D.C.

Fla.

Ga.

Ill.

Ind.

Iowa

Ky.

La.

Md.

Mass.

Mich.

Miss.

Mo.

Neb.

N.Y.

N.D.

Ohio

Okla.

Pa.

Tenn.

Texas

Va.

W.Va.

Wis.

No reported cases in 2002

Alaska

Ariz.

Hawaii

Nev.

Ore.

Utah

Bird, animal, or mosquito cases in 2003