In Galveston, the population of the island is far exceeded by the hordes of mosquitoes. While I walked from the parking garage to the building that housed my lab each morning, I was guaranteed to feed a few of the little buggers. We’ve all noticed that some people are bitten more often than others — about 20 percent of people are called high attractor types. We now know at least some of the reasons why.
The two primary ways that mosquitoes detect their prey are sight and smell. Mosquitoes use their vision, especially later in the day to search for potential prey. People wearing dark colors like black, navy blue or red stand out, and moving can also attract mosquitoes’ attention.
Once they see someone, the primary way mosquitoes home in on their prey is our exhaling of carbon dioxide, which marks a likely source of blood. The amount of carbon dioxide released varies with your metabolic rate, so drinking alcohol, exercising or simply your genetic makeup can make you more susceptible. Next time you reward yourself with a beer after mowing the lawn, do it somewhere where mosquitoes will not find you.
If you’re pregnant, your metabolic rate is elevated, making you more attractive to mosquitoes. A study has shown that pregnant women exhale 21 percent more carbon dioxide than non-pregnant women. Pregnant women also tend to have elevated body temperatures, making them even more attractive to mosquitoes.
Studies have demonstrated that odors produced by human skin contain more than 350 compounds, and we’re not sure which of these play a role in attracting mosquitoes. We know that the lactic acid produced when exercising; acetone, a metabolic byproduct that is released in breath; and estradiol, a breakdown product of estrogen, are all known mosquito attractants. People with higher levels of steroids or cholesterol may also attract more mosquitoes. Another reason to control your cholesterol.
How about blood type? Those with blood type O are the most popular, followed by B and AB about equally. Blood type A is the least attractive to mosquitoes. About 85 percent of people release a chemical signal that is indicative of their blood type, and they are more attractive to mosquitoes.
Mosquito bites are itchy, the welts they cause are a nuisance and mosquitoes can spread diseases like the Zika virus, malaria and West Nile virus. So what can you do to avoid getting bitten? Avoid being out at dawn or dusk when the mosquitoes are most active. Sit near a fan because mosquitoes have trouble flying in the breeze. Insect repellants work, but you should test out which types work on your local mosquitoes. Don’t wear dark clothing or do anything to increase your metabolism.
If all else fails, stand near someone who’s more attractive to mosquitoes than you. I had a post-doctoral research fellow in my lab from Scotland, and for his first year in Galveston, he was an amazing mosquito decoy.