These new insights might lead to a new line of clinical laboratory testing, particularly if the results could guide the patient to microbiome-based repellents that would remain effective for months once applied

Researchers are beginning to identify what compounds make individuals more attractive to mosquitos. That is a first step in the development of a biomarker that could be developed into a clinical laboratory test. Question is: would there be enough consumers wanting to do a lab test to determine if they were highly attractive to mosquitos, thus making this a revenue-generating test for labs?

It does seem like some people are mosquito magnets and there may be a scientific reason for that. According to an article published in Scientific American (SA) some people actually are more attractive to the pesky little bloodsuckers than other people. Researchers at the Laboratory of Neurogenetics and Behavior at Rockefeller University and the Howard Hughes Medical Institute (HHMI) in New York wanted to know why.

The SA article reported on their study published in the journal Cell titled, “Differential Mosquito Attraction to Humans Is Associated with Skin-Derived Carboxylic Acid Levels.” The researchers, according to SA, found that individual humans have “a unique scent profile made up of different chemical compounds” and that “mosquitoes were most drawn to people whose skin produces high levels of carboxylic acids.” The researchers also found that “attractiveness to mosquitoes remained steady over time, regardless of changes in diet or grooming habits.”

At a minimum, there would be widespread consumer interest to at least understand why some individuals get more mosquito bites than others. What may be of particular interest to microbiologists is the statement by molecular biologist Omar Akbari, PhD, of the University of California, San Diego, who told Scientific American that by “taking human-colonizing skin bacteria … and engineering them in such a way that they can either express a repellent compound or be able to degrade something that’s attractive,” a mosquito repellant could be developed that would last for months once applied.

Matthew DeGennaro, PhD

“This study clearly shows that these acids are important,” neurogeneticist Matthew DeGennaro, PhD (above), told CNN. “… how the mosquitoes perceive these carboxylic acids is interesting because these particular chemicals … are hard to smell at a distance. It could be that these chemicals are being altered by … the skin microbiome … if we understand why mosquitoes find a host, we can design new repellents that will block the mosquitoes from sensing those chemicals, and this could be used to improve our current repellents.” Clinical laboratory testing will be needed to produce biomarkers for developing such improved repellents. (Photo copyright: Laboratory of Tropical Genetics.)

Clinical Laboratory Testing Needed to Identify Levels of Carboxylic Acids

To complete their study, the researchers had 64 participants wear nylon stockings for six hours on their arms to get their unique scent into the fabric. The scent on the stockings was not discernible to the human nose, but it was to the mosquitos.

Two pieces of the nylon were then placed in a closed container with Aedes aegypti mosquitoes. The researchers found that certain samples were more popular with the mosquitos than others. Upon further analysis the researchers found that the most popular samples came from subjects with higher levels of carboxylic acids, and the least popular had the lowest levels. The scientists ran the test with the same participants several times over three years and the results remained largely the same.

Carboxylic acid is an organic compound found in humans in sebum, the oily layer protecting our skin. The level at which humans release carboxylic acid varies from person to person. And there is no discernible way the human nose can determine whether a person has the level of carboxylic acid on the skin that mosquitos find desirable. The answer would need to be determined by a diagnostic test performed in a clinical laboratory.

Although the development of a test to determine someone’s susceptibility to mosquitos may be far away, there could be significant consumer interest in developing such a test.

“The question of why some people are more attractive to mosquitoes than others—that’s the question that everybody asks,” Leslie B. Vosshall, PhD, Chief Scientific Officer, Howard Hughes Medical Institute, who led the research team to find out why some people are more attractive to mosquitos than others, told Scientific American. “My mother, my sister, people in the street, my colleagues—everybody wants to know.” She credits their interest as the inspiration for embarking on the study.

“Understanding what makes someone a ‘mosquito magnet’ will suggest ways to rationally design interventions such as skin microbiota manipulation to make people less attractive to mosquitoes. We propose that the ability to predict which individuals in a community are high attractors would allow for more effective deployment of resources to combat the spread of mosquito-borne pathogens,” the researchers wrote in their Cell paper.

Preventing Spread of Deadly Diseases

Although mosquitos are an annoyance, they also can be dangerous vectors of disease.

“Every bite of these mosquitoes puts people into public health danger. Aedes aegypti mosquitoes are vectors for dengue, yellow fever, and Zika,” Vosshall told CNN. “Those people who are magnets are going to be much more likely to be infected with viruses.”

Further research into these early findings may help develop diagnostic tests to protect against the spread of these diseases and identify individuals who are more attractive to the mosquitos, and therefore, more likely to contract and spread disease.

Being able to identify which individuals are mosquito magnets could help keep individuals safe from dangerous diseases, and development of a better repellent could also make outdoor summer events more bearable for the (unfortunately) popular among the pests. Medical laboratory tests associated with determining an individual’s susceptibility to mosquito bites could give clinical laboratories a new way to add value to consumers and patients.   

Ashley Croce

Related Information:

Some People Really Are Mosquito Magnets, and They’re Stuck That Way

Differential Mosquito Attraction to Humans Is Associated with Skin-Derived Carboxylic Acid Levels

Here’s Why Mosquitoes Are Attracted to Some People More than Others