New science explains why mosquitoes prefer some people to others

Summer is here, and mosquitoes are out.

Last year the United States confirmed 664 cases of West Nile virus, which is transmitted by tiny leeches. These cases gave rise to 52 deaths, of which the greatest number – 20 – was recorded in Texas.

So far this year, the dry heat affecting much of the West has cases up to more manageable levels. Only 11 cases and a dead person has been reported.

Why do mosquitoes seem to prefer some people more than others?

When you are in a group, you may find that you are less bitten than if you had to face the damn insect alone.

Among the more than 3,500 species of mosquitoes, of which only 200 drink human blood. Studies carried out on this smaller subset are attacked for specific characteristics which can lead to receive more or less bites.

Carbon dioxide and blood groups

With their strong sense of smell, mosquitoes can often identify best places on the body bite, usually the feet and ankles.

Researchers from London School of Hygiene and Tropical Medicine have found that human body odor and various chemical compounds can lead to more stings.

There are two compounds that our bodies naturally create that can attract mosquitoes: carbon dioxide and lactic acid. Adults tend to get bitten more frequently than children because they emit more carbon dioxide.

Later, researchers found that parasites can change the smell of a human host, making them more susceptible to mosquito bites. This is particularly dangerous in areas where Malaria and other mosquito-borne diseases are present.

A study from the American Journal of Entomology found slight differences in mosquito blood group preference. The study followed 300 mosquitoes; 192 were confirmed to have bitten a person. Thirty percent of the bugs bite someone with Type O blood.

However, the reproductive levels of insects, represented by the number of eggs laid, where the same in all blood groups.

Other studies have shown the black and red tend to attract mosquitoes, while yellow and green have been shown to keep them at bay.