Scientists have long puzzled over why mosquitoes seem to target certain individuals more than others, but a recent review offers a comprehensive explanation. Led by Professor Shengqun Deng, the study synthesizes years of research on mosquito behavior, revealing a complex interplay of factors that make one person more appealing to mosquitoes than another.
The hunt begins with a person's breath. Carbon dioxide exhaled through breath is detectable from a distance and serves as the initial trigger for mosquitoes. Larger bodies, harder breathing, and faster metabolisms increase CO2 emissions, making individuals easier to locate. Pregnancy further intensifies this effect, as women in their second trimester exhale more air, run at a higher body temperature, and emit more skin chemicals, making them more susceptible to mosquito bites.
Body odor plays a crucial role in the targeting process. Human skin emits hundreds of chemical compounds, but only a handful act as signals for mosquitoes. Carboxylic acids, produced through sweat and skin bacteria, are particularly attractive to mosquitoes. Research from Rockefeller University found that individuals with high levels of carboxylic acids on their skin were significantly more appealing to mosquitoes, with the most attractive subjects being roughly a hundred times more so than the least attractive. This chemical profile acts as a personal signature, remaining remarkably consistent from one year to the next.
A separate study involving Aedes aegypti mosquitoes and 42 women revealed that the most-bitten group, including pregnant participants, produced unusually high levels of 1-octen-3-ol, a compound with a mushroom-like scent. Even small increases in this compound were enough to shift mosquito preferences noticeably. This explains why washing the skin thoroughly or wearing freshly laundered clothes does not reliably lower bite rates, as the compounds are produced by the microbial communities living on the skin.
The review also addresses the question of blood type, noting that while one study suggests Aedes albopictus favors type O, another claims Aedes aegypti prefers type B. However, the samples are too small to draw any firm conclusions. Dark clothing and alcohol consumption can also heighten the risk of mosquito bites, as they alter exhaled CO2 and skin chemistry.
Perhaps the most intriguing aspect of this research concerns the impact of mosquito-borne illnesses. Both malaria parasites and dengue viruses appear to manipulate their human hosts to attract more mosquito bites, not as a side effect but as a survival strategy for the pathogen. In the case of malaria, a molecule called HMBPP prompts infected red blood cells to release irresistible chemical compounds. Dengue and Zika, on the other hand, alter the skin's microbial mix to produce a separate compound that pulls mosquitoes in even more strongly.
The practical implications of this research are significant. It opens the door to targeted repellents, skin treatments, and field tests that can identify individuals who are unwitting transmission hubs in malaria zones. By understanding the factors that make people more attractive to mosquitoes, we can develop more effective strategies to prevent mosquito-borne diseases and protect public health.
