It is peak mosquito season, and while some lucky outdoor venturers seem unperturbed by the tiny insects, others appear to be relentlessly assaulted. Scientists are trying to understand what makes certain humans more attractive to the bugs. One expert, molecular vector biologist L.J. Zwiebel, a professor of biological sciences at Vanderbilt University, weighs in.
Sweet Smell of Success
Mosquitoes find their mammalian prey through sensing the heat and carbon dioxide mammals emit. Pregnant women and larger people are sometimes the victim of multiple attacks, since they exert more energy than the average person.
Mosquitoes are also guided by their sense of smell. “Despite what my grandmother told me, I don’t have sweet blood,” says Dr. Zwiebel, since mosquitoes cannot distinguish blood quality. “Mosquitoes are attracted to our human odor, and that is largely a consequence of the bacteria on our skin,” says Dr. Zwiebel. The “flora and fauna on our skin” also smell appetizing to mosquitoes, says Dr. Zweibel, and these can increase when we sweat or spend a lot of time outdoors.
As far as Dr. Zwiebel knows, there is no scientific basis to prove that having high cholesterol or diabetes, despite what some websites claim, will keep bugs away. Nor will taking vitamin B supplements, eating garlic or tThis appears to be aking specific medications.
After 20 years in labs with the biting bugs, Dr. Zwiebel says he can stick his arm into a container of mozzies and be bit hundreds of times, yet “not have a hair out of place.” Children, who have been bitten far fewer times than adults, may have stronger reactions to bites, since their immune systems haven’t matured fully. But adults who are convinced they are being victimized by the bloodsuckers usually are not. “There are some people who have strong allergic responses to the bites which may make it seem like they’re being bit more often, but they’re probably not,” Dr. Zwiebel notes.
For people covered in welts and itchy wounds, Dr. Zwiebel says to stop scratching: When the mosquito bites, it leaves behind some of its saliva, a substance that contains anticoagulants and a local anesthetic, among other things. The body recognizes it as a foreign invader and sends histamines in to counterattack. Scratching just spreads the saliva and encourages the release of more antibodies, and more itching—a vicious cycle.
Those who swell up and itch a lot when bitten “should speak with their doctor about taking an over-the-counter antihistamine daily as a precaution,” says Dr. Zwiebel. The bugs will still bite, but you may not notice, since the drug prevents the allergic response that turns a painless bite into an itchy nuisance.
Cleaner Is Meaner
Female mosquitoes are driven to bite you as they need a blood meal to complete their reproductive cycle and produce fertile eggs, which takes a huge boost of protein. To reduce the chances of being bitten, wash with an antibacterial soap to reduce the volume of mosquito-attracting bacteria on your skin.
Other ways to dodge bites: Avoid the outdoors at dawn and dusk, when mosquitoes are most active. Set up an outdoor fan to shoo bugs away. And wear long trousers and shirts if it’s not too hot. Dr. Zwiebel also suggests spraying your clothing with repellent that contains DEET, a chemical that acts to confuse the mosquito’s olfactory receptors. “It works, and until something better comes along, it’s the best thing available to prevent bites,” he says.
Write to Heidi Mitchell at firstname.lastname@example.org
A version of this article appeared July 16, 2013, on page D4 in the U.S. edition of The Wall Street Journal, with the headline: BURNING QUESTION: Why do mosquitoes prefer me?.